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CC0006 Basics of Report Writing

Structure of a report (case study, literature review or survey).

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  • Citing Sources
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The information in the report has to be organised in the best possible way for the reader to understand the issue being investigated, analysis of the findings and recommendations or implications that relate directly to the findings. Given below are the main sections of a standard report. Click on each section heading to learn more about it.

  • Tells the reader what the report is about
  • Informative, short, catchy

Example - Sea level rise in Singapore : Causes, Impact and Solution

The title page must also include group name, group members and their matriculation numbers.

Content s Page

  • Has headings and subheadings that show the reader where the various sections of the report are located
  • Written on a separate page
  • Includes the page numbers of each section
  • Briefly summarises the report, the process of research and final conclusions
  • Provides a quick overview of the report and describes the main highlights
  • Short, usually not more than 150 words in length
  • Mention briefly why you choose this project, what are the implications and what kind of problems it will solve

Usually, the abstract is written last, ie. after writing the other sections and you know the key points to draw out from these sections. Abstracts allow readers who may be interested in the report to decide whether it is relevant to their purposes.

Introduction

  • Discusses the background and sets the context
  • Introduces the topic, significance of the problem, and the purpose of research
  • Gives the scope ie shows what it includes and excludes

In the introduction, write about what motivates your project, what makes it interesting, what questions do you aim to answer by doing your project. The introduction lays the foundation for understanding the research problem and should be written in a way that leads the reader from the general subject area of the topic to the particular topic of research.

Literature Review

  • Helps to gain an understanding of the existing research in that topic
  • To develop on your own ideas and build your ideas based on the existing knowledge
  • Prevents duplication of the research done by others

Search the existing literature for information. Identify the data pertinent to your topic. Review, extract the relevant information for eg how the study was conducted and the findings. Summarise the information. Write what is already known about the topic and what do the sources that you have reviewed say. Identify conflicts in previous studies, open questions, or gaps that may exist. If you are doing

  • Case study - look for background information and if any similar case studies have been done before.
  • Literature review - find out from literature, what is the background to the questions that you are looking into
  • Site visit - use the literature review to read up and prepare good questions before hand.
  • Survey - find out if similar surveys have been done before and what did they find?

Keep a record of the source details of any information you want to use in your report so that you can reference them accurately.

Methodology

Methodology is the approach that you take to gather data and arrive at the recommendation(s). Choose a method that is appropriate for the research topic and explain it in detail.

In this section, address the following: a) How the data was collected b) How it was analysed and c) Explain or justify why a particular method was chosen.

Usually, the methodology is written in the past tense and can be in the passive voice. Some examples of the different methods that you can use to gather data are given below. The data collected provides evidence to build your arguments. Collect data, integrate the findings and perspectives from different studies and add your own analysis of its feasibility.

  • Explore the literature/news/internet sources to know the topic in depth
  • Give a description of how you selected the literature for your project
  • Compare the studies, and highlight the findings, gaps or limitations.
  • An in-depth, detailed examination of specific cases within a real-world context.
  • Enables you to examine the data within a specific context.
  • Examine a well defined case to identify the essential factors, process and relationship.
  • Write the case description, the context and the process involved.
  • Make sense of the evidence in the case(s) to answer the research question
  • Gather data from a predefined group of respondents by asking relevant questions
  • Can be conducted in person or online
  • Why you chose this method (questionnaires, focus group, experimental procedure, etc)
  • How you carried out the survey. Include techniques and any equipment you used
  • If there were participants in your research, who were they? How did you select them and how may were there?
  • How the survey questions address the different aspects of the research question
  • Analyse the technology / policy approaches by visiting the required sites
  • Make a detailed report on its features and your understanding of it

Results and Analysis

  • Present the results of the study. You may consider visualising the results in tables and graphs, graphics etc.
  • Analyse the results to obtain answer to the research question.
  • Provide an analysis of the technical and financial feasibility, social acceptability etc

Discussion, Limitation(s) and Implication(s)

  • Discuss your interpretations of the analysis and the significance of your findings
  • Explain any new understanding or insights that emerged as a result of your research
  • Consider the different perspectives (social, economic and environmental)in the discussion
  • Explain the limitation(s)
  • Explain how could what you found be used to make a difference for sustainability

Conclusion and Recommendations

  • Summarise the significance and outcome of the study highlighting the key points.
  • Come up with alternatives and propose specific actions based on the alternatives
  • Describe the result or improvement it would achieve
  • Explain how it will be implemented

Recommendations should have an innovative approach and should be feasible. It should make a significant difference in solving the issue under discussion.

  • List the sources you have referred to in your writing
  • Use the recommended citation style consistently in your report

Appendix (if necessary/any)

Include any material relating to the report and research that does not fit in the body of the report, in the appendix. For example, you may include survey questionnaire and results in the appendix.

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Writing a Literature Review

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A literature review is a document or section of a document that collects key sources on a topic and discusses those sources in conversation with each other (also called synthesis ). The lit review is an important genre in many disciplines, not just literature (i.e., the study of works of literature such as novels and plays). When we say “literature review” or refer to “the literature,” we are talking about the research ( scholarship ) in a given field. You will often see the terms “the research,” “the scholarship,” and “the literature” used mostly interchangeably.

Where, when, and why would I write a lit review?

There are a number of different situations where you might write a literature review, each with slightly different expectations; different disciplines, too, have field-specific expectations for what a literature review is and does. For instance, in the humanities, authors might include more overt argumentation and interpretation of source material in their literature reviews, whereas in the sciences, authors are more likely to report study designs and results in their literature reviews; these differences reflect these disciplines’ purposes and conventions in scholarship. You should always look at examples from your own discipline and talk to professors or mentors in your field to be sure you understand your discipline’s conventions, for literature reviews as well as for any other genre.

A literature review can be a part of a research paper or scholarly article, usually falling after the introduction and before the research methods sections. In these cases, the lit review just needs to cover scholarship that is important to the issue you are writing about; sometimes it will also cover key sources that informed your research methodology.

Lit reviews can also be standalone pieces, either as assignments in a class or as publications. In a class, a lit review may be assigned to help students familiarize themselves with a topic and with scholarship in their field, get an idea of the other researchers working on the topic they’re interested in, find gaps in existing research in order to propose new projects, and/or develop a theoretical framework and methodology for later research. As a publication, a lit review usually is meant to help make other scholars’ lives easier by collecting and summarizing, synthesizing, and analyzing existing research on a topic. This can be especially helpful for students or scholars getting into a new research area, or for directing an entire community of scholars toward questions that have not yet been answered.

What are the parts of a lit review?

Most lit reviews use a basic introduction-body-conclusion structure; if your lit review is part of a larger paper, the introduction and conclusion pieces may be just a few sentences while you focus most of your attention on the body. If your lit review is a standalone piece, the introduction and conclusion take up more space and give you a place to discuss your goals, research methods, and conclusions separately from where you discuss the literature itself.

Introduction:

  • An introductory paragraph that explains what your working topic and thesis is
  • A forecast of key topics or texts that will appear in the review
  • Potentially, a description of how you found sources and how you analyzed them for inclusion and discussion in the review (more often found in published, standalone literature reviews than in lit review sections in an article or research paper)
  • Summarize and synthesize: Give an overview of the main points of each source and combine them into a coherent whole
  • Analyze and interpret: Don’t just paraphrase other researchers – add your own interpretations where possible, discussing the significance of findings in relation to the literature as a whole
  • Critically Evaluate: Mention the strengths and weaknesses of your sources
  • Write in well-structured paragraphs: Use transition words and topic sentence to draw connections, comparisons, and contrasts.

Conclusion:

  • Summarize the key findings you have taken from the literature and emphasize their significance
  • Connect it back to your primary research question

How should I organize my lit review?

Lit reviews can take many different organizational patterns depending on what you are trying to accomplish with the review. Here are some examples:

  • Chronological : The simplest approach is to trace the development of the topic over time, which helps familiarize the audience with the topic (for instance if you are introducing something that is not commonly known in your field). If you choose this strategy, be careful to avoid simply listing and summarizing sources in order. Try to analyze the patterns, turning points, and key debates that have shaped the direction of the field. Give your interpretation of how and why certain developments occurred (as mentioned previously, this may not be appropriate in your discipline — check with a teacher or mentor if you’re unsure).
  • Thematic : If you have found some recurring central themes that you will continue working with throughout your piece, you can organize your literature review into subsections that address different aspects of the topic. For example, if you are reviewing literature about women and religion, key themes can include the role of women in churches and the religious attitude towards women.
  • Qualitative versus quantitative research
  • Empirical versus theoretical scholarship
  • Divide the research by sociological, historical, or cultural sources
  • Theoretical : In many humanities articles, the literature review is the foundation for the theoretical framework. You can use it to discuss various theories, models, and definitions of key concepts. You can argue for the relevance of a specific theoretical approach or combine various theorical concepts to create a framework for your research.

What are some strategies or tips I can use while writing my lit review?

Any lit review is only as good as the research it discusses; make sure your sources are well-chosen and your research is thorough. Don’t be afraid to do more research if you discover a new thread as you’re writing. More info on the research process is available in our "Conducting Research" resources .

As you’re doing your research, create an annotated bibliography ( see our page on the this type of document ). Much of the information used in an annotated bibliography can be used also in a literature review, so you’ll be not only partially drafting your lit review as you research, but also developing your sense of the larger conversation going on among scholars, professionals, and any other stakeholders in your topic.

Usually you will need to synthesize research rather than just summarizing it. This means drawing connections between sources to create a picture of the scholarly conversation on a topic over time. Many student writers struggle to synthesize because they feel they don’t have anything to add to the scholars they are citing; here are some strategies to help you:

  • It often helps to remember that the point of these kinds of syntheses is to show your readers how you understand your research, to help them read the rest of your paper.
  • Writing teachers often say synthesis is like hosting a dinner party: imagine all your sources are together in a room, discussing your topic. What are they saying to each other?
  • Look at the in-text citations in each paragraph. Are you citing just one source for each paragraph? This usually indicates summary only. When you have multiple sources cited in a paragraph, you are more likely to be synthesizing them (not always, but often
  • Read more about synthesis here.

The most interesting literature reviews are often written as arguments (again, as mentioned at the beginning of the page, this is discipline-specific and doesn’t work for all situations). Often, the literature review is where you can establish your research as filling a particular gap or as relevant in a particular way. You have some chance to do this in your introduction in an article, but the literature review section gives a more extended opportunity to establish the conversation in the way you would like your readers to see it. You can choose the intellectual lineage you would like to be part of and whose definitions matter most to your thinking (mostly humanities-specific, but this goes for sciences as well). In addressing these points, you argue for your place in the conversation, which tends to make the lit review more compelling than a simple reporting of other sources.

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Methodology

  • What Is a Case Study? | Definition, Examples & Methods

What Is a Case Study? | Definition, Examples & Methods

Published on May 8, 2019 by Shona McCombes . Revised on November 20, 2023.

A case study is a detailed study of a specific subject, such as a person, group, place, event, organization, or phenomenon. Case studies are commonly used in social, educational, clinical, and business research.

A case study research design usually involves qualitative methods , but quantitative methods are sometimes also used. Case studies are good for describing , comparing, evaluating and understanding different aspects of a research problem .

Table of contents

When to do a case study, step 1: select a case, step 2: build a theoretical framework, step 3: collect your data, step 4: describe and analyze the case, other interesting articles.

A case study is an appropriate research design when you want to gain concrete, contextual, in-depth knowledge about a specific real-world subject. It allows you to explore the key characteristics, meanings, and implications of the case.

Case studies are often a good choice in a thesis or dissertation . They keep your project focused and manageable when you don’t have the time or resources to do large-scale research.

You might use just one complex case study where you explore a single subject in depth, or conduct multiple case studies to compare and illuminate different aspects of your research problem.

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literature review vs case study

Once you have developed your problem statement and research questions , you should be ready to choose the specific case that you want to focus on. A good case study should have the potential to:

  • Provide new or unexpected insights into the subject
  • Challenge or complicate existing assumptions and theories
  • Propose practical courses of action to resolve a problem
  • Open up new directions for future research

TipIf your research is more practical in nature and aims to simultaneously investigate an issue as you solve it, consider conducting action research instead.

Unlike quantitative or experimental research , a strong case study does not require a random or representative sample. In fact, case studies often deliberately focus on unusual, neglected, or outlying cases which may shed new light on the research problem.

Example of an outlying case studyIn the 1960s the town of Roseto, Pennsylvania was discovered to have extremely low rates of heart disease compared to the US average. It became an important case study for understanding previously neglected causes of heart disease.

However, you can also choose a more common or representative case to exemplify a particular category, experience or phenomenon.

Example of a representative case studyIn the 1920s, two sociologists used Muncie, Indiana as a case study of a typical American city that supposedly exemplified the changing culture of the US at the time.

While case studies focus more on concrete details than general theories, they should usually have some connection with theory in the field. This way the case study is not just an isolated description, but is integrated into existing knowledge about the topic. It might aim to:

  • Exemplify a theory by showing how it explains the case under investigation
  • Expand on a theory by uncovering new concepts and ideas that need to be incorporated
  • Challenge a theory by exploring an outlier case that doesn’t fit with established assumptions

To ensure that your analysis of the case has a solid academic grounding, you should conduct a literature review of sources related to the topic and develop a theoretical framework . This means identifying key concepts and theories to guide your analysis and interpretation.

There are many different research methods you can use to collect data on your subject. Case studies tend to focus on qualitative data using methods such as interviews , observations , and analysis of primary and secondary sources (e.g., newspaper articles, photographs, official records). Sometimes a case study will also collect quantitative data.

Example of a mixed methods case studyFor a case study of a wind farm development in a rural area, you could collect quantitative data on employment rates and business revenue, collect qualitative data on local people’s perceptions and experiences, and analyze local and national media coverage of the development.

The aim is to gain as thorough an understanding as possible of the case and its context.

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In writing up the case study, you need to bring together all the relevant aspects to give as complete a picture as possible of the subject.

How you report your findings depends on the type of research you are doing. Some case studies are structured like a standard scientific paper or thesis , with separate sections or chapters for the methods , results and discussion .

Others are written in a more narrative style, aiming to explore the case from various angles and analyze its meanings and implications (for example, by using textual analysis or discourse analysis ).

In all cases, though, make sure to give contextual details about the case, connect it back to the literature and theory, and discuss how it fits into wider patterns or debates.

If you want to know more about statistics , methodology , or research bias , make sure to check out some of our other articles with explanations and examples.

  • Normal distribution
  • Degrees of freedom
  • Null hypothesis
  • Discourse analysis
  • Control groups
  • Mixed methods research
  • Non-probability sampling
  • Quantitative research
  • Ecological validity

Research bias

  • Rosenthal effect
  • Implicit bias
  • Cognitive bias
  • Selection bias
  • Negativity bias
  • Status quo bias

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McCombes, S. (2023, November 20). What Is a Case Study? | Definition, Examples & Methods. Scribbr. Retrieved February 21, 2024, from https://www.scribbr.com/methodology/case-study/

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Organizing Your Social Sciences Research Paper

  • 5. The Literature Review
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A literature review surveys prior research published in books, scholarly articles, and any other sources relevant to a particular issue, area of research, or theory, and by so doing, provides a description, summary, and critical evaluation of these works in relation to the research problem being investigated. Literature reviews are designed to provide an overview of sources you have used in researching a particular topic and to demonstrate to your readers how your research fits within existing scholarship about the topic.

Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . Fourth edition. Thousand Oaks, CA: SAGE, 2014.

Importance of a Good Literature Review

A literature review may consist of simply a summary of key sources, but in the social sciences, a literature review usually has an organizational pattern and combines both summary and synthesis, often within specific conceptual categories . A summary is a recap of the important information of the source, but a synthesis is a re-organization, or a reshuffling, of that information in a way that informs how you are planning to investigate a research problem. The analytical features of a literature review might:

  • Give a new interpretation of old material or combine new with old interpretations,
  • Trace the intellectual progression of the field, including major debates,
  • Depending on the situation, evaluate the sources and advise the reader on the most pertinent or relevant research, or
  • Usually in the conclusion of a literature review, identify where gaps exist in how a problem has been researched to date.

Given this, the purpose of a literature review is to:

  • Place each work in the context of its contribution to understanding the research problem being studied.
  • Describe the relationship of each work to the others under consideration.
  • Identify new ways to interpret prior research.
  • Reveal any gaps that exist in the literature.
  • Resolve conflicts amongst seemingly contradictory previous studies.
  • Identify areas of prior scholarship to prevent duplication of effort.
  • Point the way in fulfilling a need for additional research.
  • Locate your own research within the context of existing literature [very important].

Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper. 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Jesson, Jill. Doing Your Literature Review: Traditional and Systematic Techniques . Los Angeles, CA: SAGE, 2011; Knopf, Jeffrey W. "Doing a Literature Review." PS: Political Science and Politics 39 (January 2006): 127-132; Ridley, Diana. The Literature Review: A Step-by-Step Guide for Students . 2nd ed. Los Angeles, CA: SAGE, 2012.

Types of Literature Reviews

It is important to think of knowledge in a given field as consisting of three layers. First, there are the primary studies that researchers conduct and publish. Second are the reviews of those studies that summarize and offer new interpretations built from and often extending beyond the primary studies. Third, there are the perceptions, conclusions, opinion, and interpretations that are shared informally among scholars that become part of the body of epistemological traditions within the field.

In composing a literature review, it is important to note that it is often this third layer of knowledge that is cited as "true" even though it often has only a loose relationship to the primary studies and secondary literature reviews. Given this, while literature reviews are designed to provide an overview and synthesis of pertinent sources you have explored, there are a number of approaches you could adopt depending upon the type of analysis underpinning your study.

Argumentative Review This form examines literature selectively in order to support or refute an argument, deeply embedded assumption, or philosophical problem already established in the literature. The purpose is to develop a body of literature that establishes a contrarian viewpoint. Given the value-laden nature of some social science research [e.g., educational reform; immigration control], argumentative approaches to analyzing the literature can be a legitimate and important form of discourse. However, note that they can also introduce problems of bias when they are used to make summary claims of the sort found in systematic reviews [see below].

Integrative Review Considered a form of research that reviews, critiques, and synthesizes representative literature on a topic in an integrated way such that new frameworks and perspectives on the topic are generated. The body of literature includes all studies that address related or identical hypotheses or research problems. A well-done integrative review meets the same standards as primary research in regard to clarity, rigor, and replication. This is the most common form of review in the social sciences.

Historical Review Few things rest in isolation from historical precedent. Historical literature reviews focus on examining research throughout a period of time, often starting with the first time an issue, concept, theory, phenomena emerged in the literature, then tracing its evolution within the scholarship of a discipline. The purpose is to place research in a historical context to show familiarity with state-of-the-art developments and to identify the likely directions for future research.

Methodological Review A review does not always focus on what someone said [findings], but how they came about saying what they say [method of analysis]. Reviewing methods of analysis provides a framework of understanding at different levels [i.e. those of theory, substantive fields, research approaches, and data collection and analysis techniques], how researchers draw upon a wide variety of knowledge ranging from the conceptual level to practical documents for use in fieldwork in the areas of ontological and epistemological consideration, quantitative and qualitative integration, sampling, interviewing, data collection, and data analysis. This approach helps highlight ethical issues which you should be aware of and consider as you go through your own study.

Systematic Review This form consists of an overview of existing evidence pertinent to a clearly formulated research question, which uses pre-specified and standardized methods to identify and critically appraise relevant research, and to collect, report, and analyze data from the studies that are included in the review. The goal is to deliberately document, critically evaluate, and summarize scientifically all of the research about a clearly defined research problem . Typically it focuses on a very specific empirical question, often posed in a cause-and-effect form, such as "To what extent does A contribute to B?" This type of literature review is primarily applied to examining prior research studies in clinical medicine and allied health fields, but it is increasingly being used in the social sciences.

Theoretical Review The purpose of this form is to examine the corpus of theory that has accumulated in regard to an issue, concept, theory, phenomena. The theoretical literature review helps to establish what theories already exist, the relationships between them, to what degree the existing theories have been investigated, and to develop new hypotheses to be tested. Often this form is used to help establish a lack of appropriate theories or reveal that current theories are inadequate for explaining new or emerging research problems. The unit of analysis can focus on a theoretical concept or a whole theory or framework.

NOTE : Most often the literature review will incorporate some combination of types. For example, a review that examines literature supporting or refuting an argument, assumption, or philosophical problem related to the research problem will also need to include writing supported by sources that establish the history of these arguments in the literature.

Baumeister, Roy F. and Mark R. Leary. "Writing Narrative Literature Reviews."  Review of General Psychology 1 (September 1997): 311-320; Mark R. Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Kennedy, Mary M. "Defining a Literature." Educational Researcher 36 (April 2007): 139-147; Petticrew, Mark and Helen Roberts. Systematic Reviews in the Social Sciences: A Practical Guide . Malden, MA: Blackwell Publishers, 2006; Torracro, Richard. "Writing Integrative Literature Reviews: Guidelines and Examples." Human Resource Development Review 4 (September 2005): 356-367; Rocco, Tonette S. and Maria S. Plakhotnik. "Literature Reviews, Conceptual Frameworks, and Theoretical Frameworks: Terms, Functions, and Distinctions." Human Ressource Development Review 8 (March 2008): 120-130; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016.

Structure and Writing Style

I.  Thinking About Your Literature Review

The structure of a literature review should include the following in support of understanding the research problem :

  • An overview of the subject, issue, or theory under consideration, along with the objectives of the literature review,
  • Division of works under review into themes or categories [e.g. works that support a particular position, those against, and those offering alternative approaches entirely],
  • An explanation of how each work is similar to and how it varies from the others,
  • Conclusions as to which pieces are best considered in their argument, are most convincing of their opinions, and make the greatest contribution to the understanding and development of their area of research.

The critical evaluation of each work should consider :

  • Provenance -- what are the author's credentials? Are the author's arguments supported by evidence [e.g. primary historical material, case studies, narratives, statistics, recent scientific findings]?
  • Methodology -- were the techniques used to identify, gather, and analyze the data appropriate to addressing the research problem? Was the sample size appropriate? Were the results effectively interpreted and reported?
  • Objectivity -- is the author's perspective even-handed or prejudicial? Is contrary data considered or is certain pertinent information ignored to prove the author's point?
  • Persuasiveness -- which of the author's theses are most convincing or least convincing?
  • Validity -- are the author's arguments and conclusions convincing? Does the work ultimately contribute in any significant way to an understanding of the subject?

II.  Development of the Literature Review

Four Basic Stages of Writing 1.  Problem formulation -- which topic or field is being examined and what are its component issues? 2.  Literature search -- finding materials relevant to the subject being explored. 3.  Data evaluation -- determining which literature makes a significant contribution to the understanding of the topic. 4.  Analysis and interpretation -- discussing the findings and conclusions of pertinent literature.

Consider the following issues before writing the literature review: Clarify If your assignment is not specific about what form your literature review should take, seek clarification from your professor by asking these questions: 1.  Roughly how many sources would be appropriate to include? 2.  What types of sources should I review (books, journal articles, websites; scholarly versus popular sources)? 3.  Should I summarize, synthesize, or critique sources by discussing a common theme or issue? 4.  Should I evaluate the sources in any way beyond evaluating how they relate to understanding the research problem? 5.  Should I provide subheadings and other background information, such as definitions and/or a history? Find Models Use the exercise of reviewing the literature to examine how authors in your discipline or area of interest have composed their literature review sections. Read them to get a sense of the types of themes you might want to look for in your own research or to identify ways to organize your final review. The bibliography or reference section of sources you've already read, such as required readings in the course syllabus, are also excellent entry points into your own research. Narrow the Topic The narrower your topic, the easier it will be to limit the number of sources you need to read in order to obtain a good survey of relevant resources. Your professor will probably not expect you to read everything that's available about the topic, but you'll make the act of reviewing easier if you first limit scope of the research problem. A good strategy is to begin by searching the USC Libraries Catalog for recent books about the topic and review the table of contents for chapters that focuses on specific issues. You can also review the indexes of books to find references to specific issues that can serve as the focus of your research. For example, a book surveying the history of the Israeli-Palestinian conflict may include a chapter on the role Egypt has played in mediating the conflict, or look in the index for the pages where Egypt is mentioned in the text. Consider Whether Your Sources are Current Some disciplines require that you use information that is as current as possible. This is particularly true in disciplines in medicine and the sciences where research conducted becomes obsolete very quickly as new discoveries are made. However, when writing a review in the social sciences, a survey of the history of the literature may be required. In other words, a complete understanding the research problem requires you to deliberately examine how knowledge and perspectives have changed over time. Sort through other current bibliographies or literature reviews in the field to get a sense of what your discipline expects. You can also use this method to explore what is considered by scholars to be a "hot topic" and what is not.

III.  Ways to Organize Your Literature Review

Chronology of Events If your review follows the chronological method, you could write about the materials according to when they were published. This approach should only be followed if a clear path of research building on previous research can be identified and that these trends follow a clear chronological order of development. For example, a literature review that focuses on continuing research about the emergence of German economic power after the fall of the Soviet Union. By Publication Order your sources by publication chronology, then, only if the order demonstrates a more important trend. For instance, you could order a review of literature on environmental studies of brown fields if the progression revealed, for example, a change in the soil collection practices of the researchers who wrote and/or conducted the studies. Thematic [“conceptual categories”] A thematic literature review is the most common approach to summarizing prior research in the social and behavioral sciences. Thematic reviews are organized around a topic or issue, rather than the progression of time, although the progression of time may still be incorporated into a thematic review. For example, a review of the Internet’s impact on American presidential politics could focus on the development of online political satire. While the study focuses on one topic, the Internet’s impact on American presidential politics, it would still be organized chronologically reflecting technological developments in media. The difference in this example between a "chronological" and a "thematic" approach is what is emphasized the most: themes related to the role of the Internet in presidential politics. Note that more authentic thematic reviews tend to break away from chronological order. A review organized in this manner would shift between time periods within each section according to the point being made. Methodological A methodological approach focuses on the methods utilized by the researcher. For the Internet in American presidential politics project, one methodological approach would be to look at cultural differences between the portrayal of American presidents on American, British, and French websites. Or the review might focus on the fundraising impact of the Internet on a particular political party. A methodological scope will influence either the types of documents in the review or the way in which these documents are discussed.

Other Sections of Your Literature Review Once you've decided on the organizational method for your literature review, the sections you need to include in the paper should be easy to figure out because they arise from your organizational strategy. In other words, a chronological review would have subsections for each vital time period; a thematic review would have subtopics based upon factors that relate to the theme or issue. However, sometimes you may need to add additional sections that are necessary for your study, but do not fit in the organizational strategy of the body. What other sections you include in the body is up to you. However, only include what is necessary for the reader to locate your study within the larger scholarship about the research problem.

Here are examples of other sections, usually in the form of a single paragraph, you may need to include depending on the type of review you write:

  • Current Situation : Information necessary to understand the current topic or focus of the literature review.
  • Sources Used : Describes the methods and resources [e.g., databases] you used to identify the literature you reviewed.
  • History : The chronological progression of the field, the research literature, or an idea that is necessary to understand the literature review, if the body of the literature review is not already a chronology.
  • Selection Methods : Criteria you used to select (and perhaps exclude) sources in your literature review. For instance, you might explain that your review includes only peer-reviewed [i.e., scholarly] sources.
  • Standards : Description of the way in which you present your information.
  • Questions for Further Research : What questions about the field has the review sparked? How will you further your research as a result of the review?

IV.  Writing Your Literature Review

Once you've settled on how to organize your literature review, you're ready to write each section. When writing your review, keep in mind these issues.

Use Evidence A literature review section is, in this sense, just like any other academic research paper. Your interpretation of the available sources must be backed up with evidence [citations] that demonstrates that what you are saying is valid. Be Selective Select only the most important points in each source to highlight in the review. The type of information you choose to mention should relate directly to the research problem, whether it is thematic, methodological, or chronological. Related items that provide additional information, but that are not key to understanding the research problem, can be included in a list of further readings . Use Quotes Sparingly Some short quotes are appropriate if you want to emphasize a point, or if what an author stated cannot be easily paraphrased. Sometimes you may need to quote certain terminology that was coined by the author, is not common knowledge, or taken directly from the study. Do not use extensive quotes as a substitute for using your own words in reviewing the literature. Summarize and Synthesize Remember to summarize and synthesize your sources within each thematic paragraph as well as throughout the review. Recapitulate important features of a research study, but then synthesize it by rephrasing the study's significance and relating it to your own work and the work of others. Keep Your Own Voice While the literature review presents others' ideas, your voice [the writer's] should remain front and center. For example, weave references to other sources into what you are writing but maintain your own voice by starting and ending the paragraph with your own ideas and wording. Use Caution When Paraphrasing When paraphrasing a source that is not your own, be sure to represent the author's information or opinions accurately and in your own words. Even when paraphrasing an author’s work, you still must provide a citation to that work.

V.  Common Mistakes to Avoid

These are the most common mistakes made in reviewing social science research literature.

  • Sources in your literature review do not clearly relate to the research problem;
  • You do not take sufficient time to define and identify the most relevant sources to use in the literature review related to the research problem;
  • Relies exclusively on secondary analytical sources rather than including relevant primary research studies or data;
  • Uncritically accepts another researcher's findings and interpretations as valid, rather than examining critically all aspects of the research design and analysis;
  • Does not describe the search procedures that were used in identifying the literature to review;
  • Reports isolated statistical results rather than synthesizing them in chi-squared or meta-analytic methods; and,
  • Only includes research that validates assumptions and does not consider contrary findings and alternative interpretations found in the literature.

Cook, Kathleen E. and Elise Murowchick. “Do Literature Review Skills Transfer from One Course to Another?” Psychology Learning and Teaching 13 (March 2014): 3-11; Fink, Arlene. Conducting Research Literature Reviews: From the Internet to Paper . 2nd ed. Thousand Oaks, CA: Sage, 2005; Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1998; Jesson, Jill. Doing Your Literature Review: Traditional and Systematic Techniques . London: SAGE, 2011; Literature Review Handout. Online Writing Center. Liberty University; Literature Reviews. The Writing Center. University of North Carolina; Onwuegbuzie, Anthony J. and Rebecca Frels. Seven Steps to a Comprehensive Literature Review: A Multimodal and Cultural Approach . Los Angeles, CA: SAGE, 2016; Ridley, Diana. The Literature Review: A Step-by-Step Guide for Students . 2nd ed. Los Angeles, CA: SAGE, 2012; Randolph, Justus J. “A Guide to Writing the Dissertation Literature Review." Practical Assessment, Research, and Evaluation. vol. 14, June 2009; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016; Taylor, Dena. The Literature Review: A Few Tips On Conducting It. University College Writing Centre. University of Toronto; Writing a Literature Review. Academic Skills Centre. University of Canberra.

Writing Tip

Break Out of Your Disciplinary Box!

Thinking interdisciplinarily about a research problem can be a rewarding exercise in applying new ideas, theories, or concepts to an old problem. For example, what might cultural anthropologists say about the continuing conflict in the Middle East? In what ways might geographers view the need for better distribution of social service agencies in large cities than how social workers might study the issue? You don’t want to substitute a thorough review of core research literature in your discipline for studies conducted in other fields of study. However, particularly in the social sciences, thinking about research problems from multiple vectors is a key strategy for finding new solutions to a problem or gaining a new perspective. Consult with a librarian about identifying research databases in other disciplines; almost every field of study has at least one comprehensive database devoted to indexing its research literature.

Frodeman, Robert. The Oxford Handbook of Interdisciplinarity . New York: Oxford University Press, 2010.

Another Writing Tip

Don't Just Review for Content!

While conducting a review of the literature, maximize the time you devote to writing this part of your paper by thinking broadly about what you should be looking for and evaluating. Review not just what scholars are saying, but how are they saying it. Some questions to ask:

  • How are they organizing their ideas?
  • What methods have they used to study the problem?
  • What theories have been used to explain, predict, or understand their research problem?
  • What sources have they cited to support their conclusions?
  • How have they used non-textual elements [e.g., charts, graphs, figures, etc.] to illustrate key points?

When you begin to write your literature review section, you'll be glad you dug deeper into how the research was designed and constructed because it establishes a means for developing more substantial analysis and interpretation of the research problem.

Hart, Chris. Doing a Literature Review: Releasing the Social Science Research Imagination . Thousand Oaks, CA: Sage Publications, 1 998.

Yet Another Writing Tip

When Do I Know I Can Stop Looking and Move On?

Here are several strategies you can utilize to assess whether you've thoroughly reviewed the literature:

  • Look for repeating patterns in the research findings . If the same thing is being said, just by different people, then this likely demonstrates that the research problem has hit a conceptual dead end. At this point consider: Does your study extend current research?  Does it forge a new path? Or, does is merely add more of the same thing being said?
  • Look at sources the authors cite to in their work . If you begin to see the same researchers cited again and again, then this is often an indication that no new ideas have been generated to address the research problem.
  • Search Google Scholar to identify who has subsequently cited leading scholars already identified in your literature review [see next sub-tab]. This is called citation tracking and there are a number of sources that can help you identify who has cited whom, particularly scholars from outside of your discipline. Here again, if the same authors are being cited again and again, this may indicate no new literature has been written on the topic.

Onwuegbuzie, Anthony J. and Rebecca Frels. Seven Steps to a Comprehensive Literature Review: A Multimodal and Cultural Approach . Los Angeles, CA: Sage, 2016; Sutton, Anthea. Systematic Approaches to a Successful Literature Review . Los Angeles, CA: Sage Publications, 2016.

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Evidence-Based Research: Levels of Evidence Pyramid

Introduction.

One way to organize the different types of evidence involved in evidence-based practice research is the levels of evidence pyramid. The pyramid includes a variety of evidence types and levels.

  • systematic reviews
  • critically-appraised topics
  • critically-appraised individual articles
  • randomized controlled trials
  • cohort studies
  • case-controlled studies, case series, and case reports
  • Background information, expert opinion

Levels of evidence pyramid

The levels of evidence pyramid provides a way to visualize both the quality of evidence and the amount of evidence available. For example, systematic reviews are at the top of the pyramid, meaning they are both the highest level of evidence and the least common. As you go down the pyramid, the amount of evidence will increase as the quality of the evidence decreases.

Levels of Evidence Pyramid

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EBM Pyramid and EBM Page Generator, copyright 2006 Trustees of Dartmouth College and Yale University. All Rights Reserved. Produced by Jan Glover, David Izzo, Karen Odato and Lei Wang.

Filtered Resources

Filtered resources appraise the quality of studies and often make recommendations for practice. The main types of filtered resources in evidence-based practice are:

Scroll down the page to the Systematic reviews , Critically-appraised topics , and Critically-appraised individual articles sections for links to resources where you can find each of these types of filtered information.

Systematic reviews

Authors of a systematic review ask a specific clinical question, perform a comprehensive literature review, eliminate the poorly done studies, and attempt to make practice recommendations based on the well-done studies. Systematic reviews include only experimental, or quantitative, studies, and often include only randomized controlled trials.

You can find systematic reviews in these filtered databases :

  • Cochrane Database of Systematic Reviews Cochrane systematic reviews are considered the gold standard for systematic reviews. This database contains both systematic reviews and review protocols. To find only systematic reviews, select Cochrane Reviews in the Document Type box.
  • JBI EBP Database (formerly Joanna Briggs Institute EBP Database) This database includes systematic reviews, evidence summaries, and best practice information sheets. To find only systematic reviews, click on Limits and then select Systematic Reviews in the Publication Types box. To see how to use the limit and find full text, please see our Joanna Briggs Institute Search Help page .

Open Access databases provide unrestricted access to and use of peer-reviewed and non peer-reviewed journal articles, books, dissertations, and more.

You can also find systematic reviews in this unfiltered database :

Some journals are peer reviewed

To learn more about finding systematic reviews, please see our guide:

  • Filtered Resources: Systematic Reviews

Critically-appraised topics

Authors of critically-appraised topics evaluate and synthesize multiple research studies. Critically-appraised topics are like short systematic reviews focused on a particular topic.

You can find critically-appraised topics in these resources:

  • Annual Reviews This collection offers comprehensive, timely collections of critical reviews written by leading scientists. To find reviews on your topic, use the search box in the upper-right corner.
  • Guideline Central This free database offers quick-reference guideline summaries organized by a new non-profit initiative which will aim to fill the gap left by the sudden closure of AHRQ’s National Guideline Clearinghouse (NGC).
  • JBI EBP Database (formerly Joanna Briggs Institute EBP Database) To find critically-appraised topics in JBI, click on Limits and then select Evidence Summaries from the Publication Types box. To see how to use the limit and find full text, please see our Joanna Briggs Institute Search Help page .
  • National Institute for Health and Care Excellence (NICE) Evidence-based recommendations for health and care in England.
  • Filtered Resources: Critically-Appraised Topics

Critically-appraised individual articles

Authors of critically-appraised individual articles evaluate and synopsize individual research studies.

You can find critically-appraised individual articles in these resources:

  • EvidenceAlerts Quality articles from over 120 clinical journals are selected by research staff and then rated for clinical relevance and interest by an international group of physicians. Note: You must create a free account to search EvidenceAlerts.
  • ACP Journal Club This journal publishes reviews of research on the care of adults and adolescents. You can either browse this journal or use the Search within this publication feature.
  • Evidence-Based Nursing This journal reviews research studies that are relevant to best nursing practice. You can either browse individual issues or use the search box in the upper-right corner.

To learn more about finding critically-appraised individual articles, please see our guide:

  • Filtered Resources: Critically-Appraised Individual Articles

Unfiltered resources

You may not always be able to find information on your topic in the filtered literature. When this happens, you'll need to search the primary or unfiltered literature. Keep in mind that with unfiltered resources, you take on the role of reviewing what you find to make sure it is valid and reliable.

Note: You can also find systematic reviews and other filtered resources in these unfiltered databases.

The Levels of Evidence Pyramid includes unfiltered study types in this order of evidence from higher to lower:

You can search for each of these types of evidence in the following databases:

TRIP database

Background information & expert opinion.

Background information and expert opinions are not necessarily backed by research studies. They include point-of-care resources, textbooks, conference proceedings, etc.

  • Family Physicians Inquiries Network: Clinical Inquiries Provide the ideal answers to clinical questions using a structured search, critical appraisal, authoritative recommendations, clinical perspective, and rigorous peer review. Clinical Inquiries deliver best evidence for point-of-care use.
  • Harrison, T. R., & Fauci, A. S. (2009). Harrison's Manual of Medicine . New York: McGraw-Hill Professional. Contains the clinical portions of Harrison's Principles of Internal Medicine .
  • Lippincott manual of nursing practice (8th ed.). (2006). Philadelphia, PA: Lippincott Williams & Wilkins. Provides background information on clinical nursing practice.
  • Medscape: Drugs & Diseases An open-access, point-of-care medical reference that includes clinical information from top physicians and pharmacists in the United States and worldwide.
  • Virginia Henderson Global Nursing e-Repository An open-access repository that contains works by nurses and is sponsored by Sigma Theta Tau International, the Honor Society of Nursing. Note: This resource contains both expert opinion and evidence-based practice articles.
  • Previous Page: Phrasing Research Questions
  • Next Page: Evidence Types
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What is the difference between a systematic review and a systematic literature review?

By Carol Hollier on 07-Jan-2020 12:42:03

Systematic Reviews vs Systematic Literature Reviews | IFIS Publishing

For those not immersed in systematic reviews, understanding the difference between a systematic review and a systematic literature review can be confusing.  It helps to realise that a “systematic review” is a clearly defined thing, but ambiguity creeps in around the phrase “systematic literature review” because people can and do use it in a variety of ways. 

A systematic review is a research study of research studies.  To qualify as a systematic review, a review needs to adhere to standards of transparency and reproducibility.  It will use explicit methods to identify, select, appraise, and synthesise empirical results from different but similar studies.  The study will be done in stages:  

  • In stage one, the question, which must be answerable, is framed
  • Stage two is a comprehensive literature search to identify relevant studies
  • In stage three the identified literature’s quality is scrutinised and decisions made on whether or not to include each article in the review
  • In stage four the evidence is summarised and, if the review includes a meta-analysis, the data extracted; in the final stage, findings are interpreted. [1]

Some reviews also state what degree of confidence can be placed on that answer, using the GRADE scale.  By going through these steps, a systematic review provides a broad evidence base on which to make decisions about medical interventions, regulatory policy, safety, or whatever question is analysed.   By documenting each step explicitly, the review is not only reproducible, but can be updated as more evidence on the question is generated.

Sometimes when people talk about a “systematic literature review”, they are using the phrase interchangeably with “systematic review”.  However, people can also use the phrase systematic literature review to refer to a literature review that is done in a fairly systematic way, but without the full rigor of a systematic review. 

For instance, for a systematic review, reviewers would strive to locate relevant unpublished studies in grey literature and possibly by contacting researchers directly.  Doing this is important for combatting publication bias, which is the tendency for studies with positive results to be published at a higher rate than studies with null results.  It is easy to understand how this well-documented tendency can skew a review’s findings, but someone conducting a systematic literature review in the loose sense of the phrase might, for lack of resource or capacity, forgo that step. 

Another difference might be in who is doing the research for the review. A systematic review is generally conducted by a team including an information professional for searches and a statistician for meta-analysis, along with subject experts.  Team members independently evaluate the studies being considered for inclusion in the review and compare results, adjudicating any differences of opinion.   In contrast, a systematic literature review might be conducted by one person. 

Overall, while a systematic review must comply with set standards, you would expect any review called a systematic literature review to strive to be quite comprehensive.  A systematic literature review would contrast with what is sometimes called a narrative or journalistic literature review, where the reviewer’s search strategy is not made explicit, and evidence may be cherry-picked to support an argument.

FSTA is a key tool for systematic reviews and systematic literature reviews in the sciences of food and health.

pawel-czerwinski-VkITYPupzSg-unsplash-1

The patents indexed help find results of research not otherwise publicly available because it has been done for commercial purposes.

The FSTA thesaurus will surface results that would be missed with keyword searching alone. Since the thesaurus is designed for the sciences of food and health, it is the most comprehensive for the field. 

All indexing and abstracting in FSTA is in English, so you can do your searching in English yet pick up non-English language results, and get those results translated if they meet the criteria for inclusion in a systematic review.

FSTA includes grey literature (conference proceedings) which can be difficult to find, but is important to include in comprehensive searches.

FSTA content has a deep archive. It goes back to 1969 for farm to fork research, and back to the late 1990s for food-related human nutrition literature—systematic reviews (and any literature review) should include not just the latest research but all relevant research on a question. 

You can also use FSTA to find literature reviews.

FSTA allows you to easily search for review articles (both narrative and systematic reviews) by using the subject heading or thesaurus term “REVIEWS" and an appropriate free-text keyword.

On the Web of Science or EBSCO platform, an FSTA search for reviews about cassava would look like this: DE "REVIEWS" AND cassava.

On the Ovid platform using the multi-field search option, the search would look like this: reviews.sh. AND cassava.af.

In 2011 FSTA introduced the descriptor META-ANALYSIS, making it easy to search specifically for systematic reviews that include a meta-analysis published from that year onwards.

On the EBSCO or Web of Science platform, an FSTA search for systematic reviews with meta-analyses about staphylococcus aureus would look like this: DE "META-ANALYSIS" AND staphylococcus aureus.

On the Ovid platform using the multi-field search option, the search would look like this: meta-analysis.sh. AND staphylococcus aureus.af.

Systematic reviews with meta-analyses published before 2011 are included in the REVIEWS controlled vocabulary term in the thesaurus.

An easy way to locate pre-2011 systematic reviews with meta-analyses is to search the subject heading or thesaurus term "REVIEWS" AND meta-analysis as a free-text keyword AND another appropriate free-text keyword.

On the Web of Science or EBSCO platform, the FSTA search would look like this: DE "REVIEWS" AND meta-analysis AND carbohydrate*

On the Ovid platform using the multi-field search option, the search would look like this: reviews .s h. AND meta-analysis.af. AND carbohydrate*.af.  

Related resources:

  • Literature Searching Best Practise Guide
  • Predatory publishing: Investigating researchers’ knowledge & attitudes
  • The IFIS Expert Guide to Journal Publishing

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Literature Review vs Systematic Review

  • Literature Review vs. Systematic Review
  • Primary vs. Secondary Sources
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Definitions

It’s common to confuse systematic and literature reviews because both are used to provide a summary of the existent literature or research on a specific topic. Regardless of this commonality, both types of review vary significantly. The following table provides a detailed explanation as well as the differences between systematic and literature reviews. 

Kysh, Lynn (2013): Difference between a systematic review and a literature review. [figshare]. Available at:  http://dx.doi.org/10.6084/m9.figshare.766364

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  • Korean J Anesthesiol
  • v.71(2); 2018 Apr

Introduction to systematic review and meta-analysis

1 Department of Anesthesiology and Pain Medicine, Inje University Seoul Paik Hospital, Seoul, Korea

2 Department of Anesthesiology and Pain Medicine, Chung-Ang University College of Medicine, Seoul, Korea

Systematic reviews and meta-analyses present results by combining and analyzing data from different studies conducted on similar research topics. In recent years, systematic reviews and meta-analyses have been actively performed in various fields including anesthesiology. These research methods are powerful tools that can overcome the difficulties in performing large-scale randomized controlled trials. However, the inclusion of studies with any biases or improperly assessed quality of evidence in systematic reviews and meta-analyses could yield misleading results. Therefore, various guidelines have been suggested for conducting systematic reviews and meta-analyses to help standardize them and improve their quality. Nonetheless, accepting the conclusions of many studies without understanding the meta-analysis can be dangerous. Therefore, this article provides an easy introduction to clinicians on performing and understanding meta-analyses.

Introduction

A systematic review collects all possible studies related to a given topic and design, and reviews and analyzes their results [ 1 ]. During the systematic review process, the quality of studies is evaluated, and a statistical meta-analysis of the study results is conducted on the basis of their quality. A meta-analysis is a valid, objective, and scientific method of analyzing and combining different results. Usually, in order to obtain more reliable results, a meta-analysis is mainly conducted on randomized controlled trials (RCTs), which have a high level of evidence [ 2 ] ( Fig. 1 ). Since 1999, various papers have presented guidelines for reporting meta-analyses of RCTs. Following the Quality of Reporting of Meta-analyses (QUORUM) statement [ 3 ], and the appearance of registers such as Cochrane Library’s Methodology Register, a large number of systematic literature reviews have been registered. In 2009, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement [ 4 ] was published, and it greatly helped standardize and improve the quality of systematic reviews and meta-analyses [ 5 ].

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Levels of evidence.

In anesthesiology, the importance of systematic reviews and meta-analyses has been highlighted, and they provide diagnostic and therapeutic value to various areas, including not only perioperative management but also intensive care and outpatient anesthesia [6–13]. Systematic reviews and meta-analyses include various topics, such as comparing various treatments of postoperative nausea and vomiting [ 14 , 15 ], comparing general anesthesia and regional anesthesia [ 16 – 18 ], comparing airway maintenance devices [ 8 , 19 ], comparing various methods of postoperative pain control (e.g., patient-controlled analgesia pumps, nerve block, or analgesics) [ 20 – 23 ], comparing the precision of various monitoring instruments [ 7 ], and meta-analysis of dose-response in various drugs [ 12 ].

Thus, literature reviews and meta-analyses are being conducted in diverse medical fields, and the aim of highlighting their importance is to help better extract accurate, good quality data from the flood of data being produced. However, a lack of understanding about systematic reviews and meta-analyses can lead to incorrect outcomes being derived from the review and analysis processes. If readers indiscriminately accept the results of the many meta-analyses that are published, incorrect data may be obtained. Therefore, in this review, we aim to describe the contents and methods used in systematic reviews and meta-analyses in a way that is easy to understand for future authors and readers of systematic review and meta-analysis.

Study Planning

It is easy to confuse systematic reviews and meta-analyses. A systematic review is an objective, reproducible method to find answers to a certain research question, by collecting all available studies related to that question and reviewing and analyzing their results. A meta-analysis differs from a systematic review in that it uses statistical methods on estimates from two or more different studies to form a pooled estimate [ 1 ]. Following a systematic review, if it is not possible to form a pooled estimate, it can be published as is without progressing to a meta-analysis; however, if it is possible to form a pooled estimate from the extracted data, a meta-analysis can be attempted. Systematic reviews and meta-analyses usually proceed according to the flowchart presented in Fig. 2 . We explain each of the stages below.

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Flowchart illustrating a systematic review.

Formulating research questions

A systematic review attempts to gather all available empirical research by using clearly defined, systematic methods to obtain answers to a specific question. A meta-analysis is the statistical process of analyzing and combining results from several similar studies. Here, the definition of the word “similar” is not made clear, but when selecting a topic for the meta-analysis, it is essential to ensure that the different studies present data that can be combined. If the studies contain data on the same topic that can be combined, a meta-analysis can even be performed using data from only two studies. However, study selection via a systematic review is a precondition for performing a meta-analysis, and it is important to clearly define the Population, Intervention, Comparison, Outcomes (PICO) parameters that are central to evidence-based research. In addition, selection of the research topic is based on logical evidence, and it is important to select a topic that is familiar to readers without clearly confirmed the evidence [ 24 ].

Protocols and registration

In systematic reviews, prior registration of a detailed research plan is very important. In order to make the research process transparent, primary/secondary outcomes and methods are set in advance, and in the event of changes to the method, other researchers and readers are informed when, how, and why. Many studies are registered with an organization like PROSPERO ( http://www.crd.york.ac.uk/PROSPERO/ ), and the registration number is recorded when reporting the study, in order to share the protocol at the time of planning.

Defining inclusion and exclusion criteria

Information is included on the study design, patient characteristics, publication status (published or unpublished), language used, and research period. If there is a discrepancy between the number of patients included in the study and the number of patients included in the analysis, this needs to be clearly explained while describing the patient characteristics, to avoid confusing the reader.

Literature search and study selection

In order to secure proper basis for evidence-based research, it is essential to perform a broad search that includes as many studies as possible that meet the inclusion and exclusion criteria. Typically, the three bibliographic databases Medline, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL) are used. In domestic studies, the Korean databases KoreaMed, KMBASE, and RISS4U may be included. Effort is required to identify not only published studies but also abstracts, ongoing studies, and studies awaiting publication. Among the studies retrieved in the search, the researchers remove duplicate studies, select studies that meet the inclusion/exclusion criteria based on the abstracts, and then make the final selection of studies based on their full text. In order to maintain transparency and objectivity throughout this process, study selection is conducted independently by at least two investigators. When there is a inconsistency in opinions, intervention is required via debate or by a third reviewer. The methods for this process also need to be planned in advance. It is essential to ensure the reproducibility of the literature selection process [ 25 ].

Quality of evidence

However, well planned the systematic review or meta-analysis is, if the quality of evidence in the studies is low, the quality of the meta-analysis decreases and incorrect results can be obtained [ 26 ]. Even when using randomized studies with a high quality of evidence, evaluating the quality of evidence precisely helps determine the strength of recommendations in the meta-analysis. One method of evaluating the quality of evidence in non-randomized studies is the Newcastle-Ottawa Scale, provided by the Ottawa Hospital Research Institute 1) . However, we are mostly focusing on meta-analyses that use randomized studies.

If the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) system ( http://www.gradeworkinggroup.org/ ) is used, the quality of evidence is evaluated on the basis of the study limitations, inaccuracies, incompleteness of outcome data, indirectness of evidence, and risk of publication bias, and this is used to determine the strength of recommendations [ 27 ]. As shown in Table 1 , the study limitations are evaluated using the “risk of bias” method proposed by Cochrane 2) . This method classifies bias in randomized studies as “low,” “high,” or “unclear” on the basis of the presence or absence of six processes (random sequence generation, allocation concealment, blinding participants or investigators, incomplete outcome data, selective reporting, and other biases) [ 28 ].

The Cochrane Collaboration’s Tool for Assessing the Risk of Bias [ 28 ]

Data extraction

Two different investigators extract data based on the objectives and form of the study; thereafter, the extracted data are reviewed. Since the size and format of each variable are different, the size and format of the outcomes are also different, and slight changes may be required when combining the data [ 29 ]. If there are differences in the size and format of the outcome variables that cause difficulties combining the data, such as the use of different evaluation instruments or different evaluation timepoints, the analysis may be limited to a systematic review. The investigators resolve differences of opinion by debate, and if they fail to reach a consensus, a third-reviewer is consulted.

Data Analysis

The aim of a meta-analysis is to derive a conclusion with increased power and accuracy than what could not be able to achieve in individual studies. Therefore, before analysis, it is crucial to evaluate the direction of effect, size of effect, homogeneity of effects among studies, and strength of evidence [ 30 ]. Thereafter, the data are reviewed qualitatively and quantitatively. If it is determined that the different research outcomes cannot be combined, all the results and characteristics of the individual studies are displayed in a table or in a descriptive form; this is referred to as a qualitative review. A meta-analysis is a quantitative review, in which the clinical effectiveness is evaluated by calculating the weighted pooled estimate for the interventions in at least two separate studies.

The pooled estimate is the outcome of the meta-analysis, and is typically explained using a forest plot ( Figs. 3 and ​ and4). 4 ). The black squares in the forest plot are the odds ratios (ORs) and 95% confidence intervals in each study. The area of the squares represents the weight reflected in the meta-analysis. The black diamond represents the OR and 95% confidence interval calculated across all the included studies. The bold vertical line represents a lack of therapeutic effect (OR = 1); if the confidence interval includes OR = 1, it means no significant difference was found between the treatment and control groups.

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Forest plot analyzed by two different models using the same data. (A) Fixed-effect model. (B) Random-effect model. The figure depicts individual trials as filled squares with the relative sample size and the solid line as the 95% confidence interval of the difference. The diamond shape indicates the pooled estimate and uncertainty for the combined effect. The vertical line indicates the treatment group shows no effect (OR = 1). Moreover, if the confidence interval includes 1, then the result shows no evidence of difference between the treatment and control groups.

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Forest plot representing homogeneous data.

Dichotomous variables and continuous variables

In data analysis, outcome variables can be considered broadly in terms of dichotomous variables and continuous variables. When combining data from continuous variables, the mean difference (MD) and standardized mean difference (SMD) are used ( Table 2 ).

Summary of Meta-analysis Methods Available in RevMan [ 28 ]

The MD is the absolute difference in mean values between the groups, and the SMD is the mean difference between groups divided by the standard deviation. When results are presented in the same units, the MD can be used, but when results are presented in different units, the SMD should be used. When the MD is used, the combined units must be shown. A value of “0” for the MD or SMD indicates that the effects of the new treatment method and the existing treatment method are the same. A value lower than “0” means the new treatment method is less effective than the existing method, and a value greater than “0” means the new treatment is more effective than the existing method.

When combining data for dichotomous variables, the OR, risk ratio (RR), or risk difference (RD) can be used. The RR and RD can be used for RCTs, quasi-experimental studies, or cohort studies, and the OR can be used for other case-control studies or cross-sectional studies. However, because the OR is difficult to interpret, using the RR and RD, if possible, is recommended. If the outcome variable is a dichotomous variable, it can be presented as the number needed to treat (NNT), which is the minimum number of patients who need to be treated in the intervention group, compared to the control group, for a given event to occur in at least one patient. Based on Table 3 , in an RCT, if x is the probability of the event occurring in the control group and y is the probability of the event occurring in the intervention group, then x = c/(c + d), y = a/(a + b), and the absolute risk reduction (ARR) = x − y. NNT can be obtained as the reciprocal, 1/ARR.

Calculation of the Number Needed to Treat in the Dichotomous table

Fixed-effect models and random-effect models

In order to analyze effect size, two types of models can be used: a fixed-effect model or a random-effect model. A fixed-effect model assumes that the effect of treatment is the same, and that variation between results in different studies is due to random error. Thus, a fixed-effect model can be used when the studies are considered to have the same design and methodology, or when the variability in results within a study is small, and the variance is thought to be due to random error. Three common methods are used for weighted estimation in a fixed-effect model: 1) inverse variance-weighted estimation 3) , 2) Mantel-Haenszel estimation 4) , and 3) Peto estimation 5) .

A random-effect model assumes heterogeneity between the studies being combined, and these models are used when the studies are assumed different, even if a heterogeneity test does not show a significant result. Unlike a fixed-effect model, a random-effect model assumes that the size of the effect of treatment differs among studies. Thus, differences in variation among studies are thought to be due to not only random error but also between-study variability in results. Therefore, weight does not decrease greatly for studies with a small number of patients. Among methods for weighted estimation in a random-effect model, the DerSimonian and Laird method 6) is mostly used for dichotomous variables, as the simplest method, while inverse variance-weighted estimation is used for continuous variables, as with fixed-effect models. These four methods are all used in Review Manager software (The Cochrane Collaboration, UK), and are described in a study by Deeks et al. [ 31 ] ( Table 2 ). However, when the number of studies included in the analysis is less than 10, the Hartung-Knapp-Sidik-Jonkman method 7) can better reduce the risk of type 1 error than does the DerSimonian and Laird method [ 32 ].

Fig. 3 shows the results of analyzing outcome data using a fixed-effect model (A) and a random-effect model (B). As shown in Fig. 3 , while the results from large studies are weighted more heavily in the fixed-effect model, studies are given relatively similar weights irrespective of study size in the random-effect model. Although identical data were being analyzed, as shown in Fig. 3 , the significant result in the fixed-effect model was no longer significant in the random-effect model. One representative example of the small study effect in a random-effect model is the meta-analysis by Li et al. [ 33 ]. In a large-scale study, intravenous injection of magnesium was unrelated to acute myocardial infarction, but in the random-effect model, which included numerous small studies, the small study effect resulted in an association being found between intravenous injection of magnesium and myocardial infarction. This small study effect can be controlled for by using a sensitivity analysis, which is performed to examine the contribution of each of the included studies to the final meta-analysis result. In particular, when heterogeneity is suspected in the study methods or results, by changing certain data or analytical methods, this method makes it possible to verify whether the changes affect the robustness of the results, and to examine the causes of such effects [ 34 ].

Heterogeneity

Homogeneity test is a method whether the degree of heterogeneity is greater than would be expected to occur naturally when the effect size calculated from several studies is higher than the sampling error. This makes it possible to test whether the effect size calculated from several studies is the same. Three types of homogeneity tests can be used: 1) forest plot, 2) Cochrane’s Q test (chi-squared), and 3) Higgins I 2 statistics. In the forest plot, as shown in Fig. 4 , greater overlap between the confidence intervals indicates greater homogeneity. For the Q statistic, when the P value of the chi-squared test, calculated from the forest plot in Fig. 4 , is less than 0.1, it is considered to show statistical heterogeneity and a random-effect can be used. Finally, I 2 can be used [ 35 ].

I 2 , calculated as shown above, returns a value between 0 and 100%. A value less than 25% is considered to show strong homogeneity, a value of 50% is average, and a value greater than 75% indicates strong heterogeneity.

Even when the data cannot be shown to be homogeneous, a fixed-effect model can be used, ignoring the heterogeneity, and all the study results can be presented individually, without combining them. However, in many cases, a random-effect model is applied, as described above, and a subgroup analysis or meta-regression analysis is performed to explain the heterogeneity. In a subgroup analysis, the data are divided into subgroups that are expected to be homogeneous, and these subgroups are analyzed. This needs to be planned in the predetermined protocol before starting the meta-analysis. A meta-regression analysis is similar to a normal regression analysis, except that the heterogeneity between studies is modeled. This process involves performing a regression analysis of the pooled estimate for covariance at the study level, and so it is usually not considered when the number of studies is less than 10. Here, univariate and multivariate regression analyses can both be considered.

Publication bias

Publication bias is the most common type of reporting bias in meta-analyses. This refers to the distortion of meta-analysis outcomes due to the higher likelihood of publication of statistically significant studies rather than non-significant studies. In order to test the presence or absence of publication bias, first, a funnel plot can be used ( Fig. 5 ). Studies are plotted on a scatter plot with effect size on the x-axis and precision or total sample size on the y-axis. If the points form an upside-down funnel shape, with a broad base that narrows towards the top of the plot, this indicates the absence of a publication bias ( Fig. 5A ) [ 29 , 36 ]. On the other hand, if the plot shows an asymmetric shape, with no points on one side of the graph, then publication bias can be suspected ( Fig. 5B ). Second, to test publication bias statistically, Begg and Mazumdar’s rank correlation test 8) [ 37 ] or Egger’s test 9) [ 29 ] can be used. If publication bias is detected, the trim-and-fill method 10) can be used to correct the bias [ 38 ]. Fig. 6 displays results that show publication bias in Egger’s test, which has then been corrected using the trim-and-fill method using Comprehensive Meta-Analysis software (Biostat, USA).

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Funnel plot showing the effect size on the x-axis and sample size on the y-axis as a scatter plot. (A) Funnel plot without publication bias. The individual plots are broader at the bottom and narrower at the top. (B) Funnel plot with publication bias. The individual plots are located asymmetrically.

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Funnel plot adjusted using the trim-and-fill method. White circles: comparisons included. Black circles: inputted comparisons using the trim-and-fill method. White diamond: pooled observed log risk ratio. Black diamond: pooled inputted log risk ratio.

Result Presentation

When reporting the results of a systematic review or meta-analysis, the analytical content and methods should be described in detail. First, a flowchart is displayed with the literature search and selection process according to the inclusion/exclusion criteria. Second, a table is shown with the characteristics of the included studies. A table should also be included with information related to the quality of evidence, such as GRADE ( Table 4 ). Third, the results of data analysis are shown in a forest plot and funnel plot. Fourth, if the results use dichotomous data, the NNT values can be reported, as described above.

The GRADE Evidence Quality for Each Outcome

N: number of studies, ROB: risk of bias, PON: postoperative nausea, POV: postoperative vomiting, PONV: postoperative nausea and vomiting, CI: confidence interval, RR: risk ratio, AR: absolute risk.

When Review Manager software (The Cochrane Collaboration, UK) is used for the analysis, two types of P values are given. The first is the P value from the z-test, which tests the null hypothesis that the intervention has no effect. The second P value is from the chi-squared test, which tests the null hypothesis for a lack of heterogeneity. The statistical result for the intervention effect, which is generally considered the most important result in meta-analyses, is the z-test P value.

A common mistake when reporting results is, given a z-test P value greater than 0.05, to say there was “no statistical significance” or “no difference.” When evaluating statistical significance in a meta-analysis, a P value lower than 0.05 can be explained as “a significant difference in the effects of the two treatment methods.” However, the P value may appear non-significant whether or not there is a difference between the two treatment methods. In such a situation, it is better to announce “there was no strong evidence for an effect,” and to present the P value and confidence intervals. Another common mistake is to think that a smaller P value is indicative of a more significant effect. In meta-analyses of large-scale studies, the P value is more greatly affected by the number of studies and patients included, rather than by the significance of the results; therefore, care should be taken when interpreting the results of a meta-analysis.

When performing a systematic literature review or meta-analysis, if the quality of studies is not properly evaluated or if proper methodology is not strictly applied, the results can be biased and the outcomes can be incorrect. However, when systematic reviews and meta-analyses are properly implemented, they can yield powerful results that could usually only be achieved using large-scale RCTs, which are difficult to perform in individual studies. As our understanding of evidence-based medicine increases and its importance is better appreciated, the number of systematic reviews and meta-analyses will keep increasing. However, indiscriminate acceptance of the results of all these meta-analyses can be dangerous, and hence, we recommend that their results be received critically on the basis of a more accurate understanding.

1) http://www.ohri.ca .

2) http://methods.cochrane.org/bias/assessing-risk-bias-included-studies .

3) The inverse variance-weighted estimation method is useful if the number of studies is small with large sample sizes.

4) The Mantel-Haenszel estimation method is useful if the number of studies is large with small sample sizes.

5) The Peto estimation method is useful if the event rate is low or one of the two groups shows zero incidence.

6) The most popular and simplest statistical method used in Review Manager and Comprehensive Meta-analysis software.

7) Alternative random-effect model meta-analysis that has more adequate error rates than does the common DerSimonian and Laird method, especially when the number of studies is small. However, even with the Hartung-Knapp-Sidik-Jonkman method, when there are less than five studies with very unequal sizes, extra caution is needed.

8) The Begg and Mazumdar rank correlation test uses the correlation between the ranks of effect sizes and the ranks of their variances [ 37 ].

9) The degree of funnel plot asymmetry as measured by the intercept from the regression of standard normal deviates against precision [ 29 ].

10) If there are more small studies on one side, we expect the suppression of studies on the other side. Trimming yields the adjusted effect size and reduces the variance of the effects by adding the original studies back into the analysis as a mirror image of each study.

  • Open access
  • Published: 13 February 2024

Secondary peripheral chondrosarcoma in multiple osteochondromas: a retrospective single-institution case series

  • Maria Gnoli   ORCID: orcid.org/0000-0002-5907-7470 1 ,
  • Marco Gambarotti 2 ,
  • Alberto Righi 2 ,
  • Eric Lodewijk Staals 3 ,
  • Andrea Evangelista 4 ,
  • Morena Tremosini 1 ,
  • Evelise Brizola 1 ,
  • Marina Mordenti   ORCID: orcid.org/0000-0002-2085-3065 1 ,
  • Manila Boarini   ORCID: orcid.org/0000-0002-9156-1772 1 ,
  • Manuela Locatelli   ORCID: orcid.org/0000-0002-7594-8774 1 ,
  • Elena Pedrini   ORCID: orcid.org/0000-0001-9980-7741 1 &
  • Luca Sangiorgi   ORCID: orcid.org/0000-0003-3658-1209 1  

Orphanet Journal of Rare Diseases volume  19 , Article number:  63 ( 2024 ) Cite this article

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Metrics details

Multiple osteochondromas is genetic disorder characterized by the formation of multiple benign cartilage-capped bone tumors, named osteochondromas, during skeletal development. The most feared complication is the secondary peripheral chondrosarcoma, a malignant cartilaginous neoplasm that arises from the chondroid cap of pre-existent osteochondromas. We conducted a retrospective cohort study on patients diagnosed and followed up from 1960 to 2019 to describe the clinical and pathological features of individuals affected by peripheral chondrosarcoma in multiple osteochondromas, to evaluate follow up information and individual outcome and to compare the results with literature. Data, including age, gender, site, histological grade, cartilage cap thickness, surgical treatments, surgical margins, genotype mutational status as well as treatment details were captured from the hospital electronic health records and from Registry of Multiple Osteochondromas. In addition, a complete histological review of all hematoxylin and eosin (H&E)-stained sections has been performed by expert pathologists.

One hundred five of the screened cases were included in the present study. The age at diagnosis of SPC ranges from 13 to 63, with median age at diagnosis of 34 years. The site most frequently affected by malignant degeneration was the pelvis (46 patients, 44%) with higher incidence in male patients (32 males vs.14 females). The second one was lower limbs (including femur, fibula, or tibia), identified in 35 patients. Histological information - available for 103 patients – showed: 59 patients with grade 1; 40 patients had a grade 2 and 4 patients had a grade 3. The most common surgical treatment was the complete resection, followed by debulking, amputation and partial resection. Most of cases did not have recurrence of the disease. Outcome in disease-free survival highlights that a worse course of the disease was associated with histological grade 2 or 3, and partial resection surgery. In most of analyzed cases (94%) a pathogenic variant was identified.

Conclusions

In conclusion, the present study gives an overview of the secondary peripheral chondrosarcomas, confirming that this disease represents an impacting complication for multiple osteochondromas patients and suggests that malignant transformation can occur also in younger patient, in a not irrelevant number of cases.

Introduction

Multiple Osteochondromas (MO – MIM# 133,700 and MIM# 133,701) [ 1 , 2 ] is an autosomal dominant rare bone dysplasia frequently defined as Hereditary Multiple Exostoses with a European-based incidence of at least 1:50.000. The representative clinical hallmark are osteochondromas (OCs), benign cartilage-capped bony tumors, that arise on long bones [ 3 ]. OCs grow in size and number during childhood until skeletal maturity [ 1 , 4 , 5 ]. Germline pathogenic variants either on EXT1 [MIM *608177] or EXT2 [MIM *608210] have been identified in the vast majority of MO patients [ 6 , 7 , 8 ]. Since EXT1 and EXT2 encode for Golgi-resident glycosyltransferases in charge of heparan sulfate chain synthesis, pathogenic variants on those genes result in systemic heparan sulfate deficiency, impacting on can affect diverse physiologic processes [ 3 ].

Malignant degeneration of an osteochondroma in chondrosarcoma is the most serious complication, which is estimated to occur in 0.5–5% of patients [ 1 ]. An increase in size of a lesion after puberty and the presence of pain in adults are signs that raise suspicion of a Secondary Peripheral Chondrosarcoma (SPC). In addition, the most reliable feature to suspect a SPC is the cartilaginous cap thickness (exceeding 1.5–2 cm) [ 9 ]. Moreover, the imaging or the histology per se may not be distinguish an osteochondroma from low-grade peripheral chondrosarcoma because the diagnosis needs specialized bone tumor pathologists as well as a multidisciplinary approach [ 10 ].

At present, the real overall incidence of this event in MO and the risk by age, sex, genotype, and skeletal site is not well known, because of the variability of these values in medical literature [ 2 , 11 , 12 ], even if the male gender tends to have a higher risk of malignant transformation [ 13 ].

The available studies in medical literature often did not provide detailed information about malignant transformation in MO or suffered by some bias; in particular, some studies are based on anonymous web-based survey, with self-reported information by the patient, without follow-up details. Other studies were performed on small series or large series collected in tertiary referral institutions; these populations can be not representative of MO patients, so the inclusion of milder forms is limited, and patients not requiring medical treatment or not diagnosed forms are missing [ 2 , 12 , 14 , 15 , 16 , 17 ]. While information is available about survival in chondrosarcoma [ 18 ], no specific literature on survival rates for chondrosarcomas in MO series is available [ 19 ].

The aim of the present study is to evaluate a series of 105 MO adult and adolescent patients - stratified by gender - who underwent chondrosarcoma diagnosis with regard to the role of some factors (i.e., age, site, histological grade, cartilage cap thickness, types of surgical treatment, status of surgical margins, EXT1/EXT2 genotype mutational status) in risk of developing this complication, and the relationship of these factors to individual outcome.

Patients and methods

Study design and data collection.

We conducted a retrospective cohort study in SPC cases diagnosed at the IRCCS Istituto Ortopedico Rizzoli from 1960 to 2019. Clinical and radiological data, treatment details and follow-up information were captured from the hospital (electronic) health records and from the Registry of Multiple Osteochondromas (Registro delle Esostosi Multiple, REM - NCT04133285) [ 20 ] and paper-based information were digitalized for the aim of the present study.

The presence of osteochondromas was confirmed clinically and radiologically and the diagnosis was made in a multidisciplinary setting (clinical, radiological, pathological experts as well as surgeons), considering individual case characteristics (i.e. age at diagnosis). This series included patients with adequate available material, that has been entirely revised for all histological features, applying to all samples the criteria published by the World Health Organization Classification of Tumors of Soft Tissue and Bone (WHO 2020). In fact, all H&E-stained sections were re-evaluated by two pathologists. The histological grade was confirmed or re-assessed as follow: the diagnosis of grade 1 peripheral chondrosarcoma was made according to the criteria described in the last WHO (2020). The most important feature was the thickness of the cartilaginous cap > 2 cm; a lobular pattern with nodules in the surrounding soft tissue, separated by the mail mass, and the invasion of the stalk of the osteochondroma were also in favor of malignancy. Mitosis and nuclear pleomorphism in such setting defined grade 2 and 3.The types of surgical treatment (complete resection, partial resection, debulking and amputation) has been decided taking into account the definition of margins of the Musculoskeletal Tumor Society as defined by Enneking et al. [ 21 ]: wide (the presence of normal tissue between tumor and margin), marginal (resection along the pseudocapsule or reactive zone around the tumor), intralesional (macroscopic or microscopic tumor at the margin) and radical (an entire anatomical compartment excised).

The anatomical site of the neoplasms was established by radiological evaluation. Maximum linear dimension and cartilaginous caps of tumors were measured either radiologically or by gross examination, when possible.

The present study was approved by the independent review committee “Comitato Etico di Area Vasta Emilia Centro” in November 2020 (929/2020/Oss/IOR) and performed in accordance with the ethical standards in the 1964 Declaration of Helsinki.

Molecular screening

Molecular screening results, performed between 2004 and 2020, were available for 50 cases. All coding exons and flanking exon-intron junctions of EXT1 and EXT2 were evaluated by Sanger sequencing using the ABI PRISM 3500XL Genetic Analyzer (Thermo Fisher Scientific, Waltham, MA, USA) for the presence of point mutations; in case of negative results, both genes were evaluated by MLPA (Multiple Ligation-dependent Probe Amplification) analysis for the presence of exon or multi-exons deletion/amplification as previously described [ 22 ].

Statistical analysis

Patients’ characteristics, stratified by gender, were reported using medians (with interquartile range, IQR) and percentages for continuous and categorical variables, respectively. For each patient, the Disease-Free Survival (DFS) was calculated from the date of diagnosis to local recurrence, metastasis (MTS) onset or death as a result of the disease. DFS were estimated with the Kaplan-Meier method and then compared between groups with the log-rank test. The Cox proportional hazard model was used to estimate the Hazard ratios (HRs). A multivariable Cox model for DFS by including all evaluated patients was estimated using multiple imputation to account for missing data in patient characteristics. The combined estimates were then obtained from 25 imputed data sets. A p-value < 0.05 was considered statistically significant. All analyses were performed with Stata 11.2 (StataCorp®, College Station, TX, USA).

This study includes 105 MO - for the large majority Caucasian Italian - patients − 74 male and 31 female - affected by SPC - that were evaluated at the IRCCS Istituto Ortopedico Rizzoli. Overall, 888 OCs that underwent to surgical intervention at IRCCS Istituto Ortopedico Rizzoli were screened, among them 215 where chondrosarcomas arising from solitary osteochondromas, while 105 (11.82%) were diagnosed as SPC in MO. A summary of clinical, pathological, and molecular information is described in Table  1 .

Demographical features

The age at diagnosis of SPC ranges from 13 to 63 years, with an overall median age at diagnosis of 34 years (IQR 26.5–44). In male patients, the median age at diagnosis of SPC was 33.5 years, while in female patients was 37 years. Cases from 20 to 40 years old represent the 60% of the cases.

Our series comprises also patients younger than 30 years, including, 7 teenager patients had low grade SPC, except one. Six cases had pelvic region involvement (pelvis or proximal femur), and one case of vertebral SPC who underwent to partial resection and showed a recurrence of the disease about 10 years later.

Among 105 patients, 32 (26 males and 6 females) were under 30 years (30%); in 18 of them the pelvis region or the proximal femur were involved and 16 developed grade 2 chondrosarcomas.

Fifty-four patients were between 30 and 49 years old (56.7%); the most affected site is the pelvis (26 subjects), followed by 11 patients with involvement at femur.

Among the 18 older patients – over 50 years of age – the most frequent SPC site is the pelvis (10 patients).

About 30% of cases were over 40 years old and among them the most (60% of case) had a low-grade lesion.

Only 6 patients were older than 50 years had a grade 2 or 3 lesion. Five out of six had a grade 2 SPC, while one developed grade 3 tumor.

Clinical, surgical, and histological features

About the site of malignant degeneration, axial skeleton was involved in 57% of cases. Pelvis was affected in the most of cases (46 patients, 44%) with higher incidence in male patients (32 males vs.14 females, 70% and 30%, respectively).

The second most frequent site was lower limbs (femur or fibula or tibia), identified in 35 patients (33%), 23 males (65.7%) and 12 females (34.3%), in particular, proximal femur was involved in 17 cases.

The upper limb (6 cases) and the spine (6 cases mainly involving cervical vertebrae (C3, C4, C5 and C7)) represented about 6% of cases, followed by scapula (5 patients). The rib was the site of malignant transformation in 3 cases (3%). A patient had a malignant transformation of calcaneal region OC and another patient at clavicle (Tables  2 and 3 ).

Taking into consideration the tumor grade, histological information was available for 103 patients: fifty-nine patients (57%, 37 males and 22 females) had grade 1 SPC; 40 patients (39%, 33 males and 7 females) had a grade 2 and just 4 patients (3 males and 1 female) had a grade 3.

The mean age of diagnosis in grade 1 SPCs was 37 years, 35 years for grade 2 and 38.5 years for the grade 3 cases.

In 69 cases out of 103, the cartilaginous cap thickness was captured, with a median width of 3 cm, ranging from 2.2 to 5.5 cm.

Diameter of the SPC lesion ranges from 8.5 to 14.6 cm (median 11 cm) for the 78 cases where this information was available.

Information about surgical treatment was provided for 97 patients, 44 of them (45.36%) had a complete resection of the lesion, 9 of them (9.28%) had a partial resection, 29 (29.90%) debulking and 15 (15.46%) amputation.

Taking into consideration the follow-up, 83 of 105 cases (79%) did not have recurrence of the disease neither metastasis, instead a local recurrence was reported in 22 cases (21%). Eight patients (all males) were known to have distal metastasis, in these cases the affected site was pelvis or proximal femur, and the grade was 2 for most of them (7 cases).

As outlined by the Fig.  1 A-B, we observe a statistically significant different outcome in Disease-Free Survival in cases treated with a more radical surgery respect to partial resection.

figure 1

Disease-free survival from histological report. 1A : Graphical Disease-Free Survival for the entire follow up period. 1B : Detailed data at 5 and 10 years of follow up from histological reports

At the latest follow-up (December 2020), 97 patients were alive (66 males and all 31 females), while 8 patients died, 3 of them due to the disease. Factors associated to a worse course of the disease were histological grade 2 and 3, and partial resection surgery. Multivariable analysis on Disease-free Survival (DFS) (Recurrence/MTS free Survival) showed that histological grade ≥ 2 (HR 5.22, p 0.003) and partial resection (HR 34.47, p < 0.001) were significantly associated to recurrence of the disease (Fig.  2 A-B).

figure 2

Disease-free survival from histological report considering factors associated to worse disease course. 2A : Histological grade. 2B : Type of surgical treatment

Molecular evaluation and inheritance

Molecular results of EXT genes analysis were available for 50 patients.

In 47 cases (34 males and 13 females), a pathogenic variant was identified, in particular 31 patients (66%, 21 males and 10 females) carry a disease-causing variant on EXT1 gene, while an EXT2 causative variant was found in 16 patients (34%, 16 males and 3 females). No pathogenic or unknown significance variants were identified on EXT genes in 3 patients (6%, 2 males and 1 female). Variant are listed in Table  4 .

Information about the family history was available for 53 out of 105 cases of chondrosarcoma. Thirty-seven patients (28 males and 9 females) inherited the disease from a parent; none of the females’ patients had recurrence of disease and 3 out of 28 males were found to have a recurrence of the disease after surgery.

In the subset of patients with molecular analysis, no strong genotype-phenotype correlation can be made, in particular on SPC, mainly due to the limited number of cases.

Malignant transformation is known to be the most serious complication of MO disease. A higher risk of SPC in patients with multiple osteochondromas is known since 1983 [ 23 ]. Nevertheless, the real incidence, the age of onset, and the specific risk factors for chondrosarcoma development in MO are at present not well assessed. In fact, few studies of large series or systematically focused on SPC are available in medical literature [ 19 ].

In this paper we describe clinical and histological findings and genetic background of a large series of SPC in MO patients.

This study has some limitations. At first, being a reference center of expertise for MO in Italy and a surgery institution, our series can have a selection bias for patients who underwent surgery, with either a higher suspect of malignant degeneration, or a more severe phenotype with a more frequent indication for surgery of an OC. This can negatively impact on number of milder cases (characterized by less health complaint and no need of surgical intervention), leading to a series not completely representative of whole MO population. On the other hand, the evaluated series is very large, including 105 SPC in MO.

The overall chondrosarcoma prevalence we calculated did not encompass these cases in general MO populations, consequently, can be overestimated. At the other hand, because the diagnosis was performed in the same Institution, with expertise in the disease, all the cases are evaluated with homogeneous criteria.

In addition, almost 60 cases underwent surgical treatment before 1990’s, so clinical, imaging and follow-data were collected with different criteria, nevertheless all available pathological samples have been revised by expert pathologists.

In this study we observe a median age at SPC diagnosis of 34 years in line with the reported in medical literature: the review by Fei and colleagues described that 80% of the chondrosarcoma cases occurs before the age 40 (between ages 20 and 40) [ 19 ]. This highlighted that onset of this complication in MO is anticipated than the primary chondrosarcomas (ages 30–60) [ 24 ]. Previously mean age of degeneration onset in MO was estimated at 31 years [ 25 ], moreover, some following reports individuated different age of onset, describing a mean age of about 29 years (± 9.3 years), [ 14 ] or 35 years [ 26 ].

SPC onset in MO is thought to occur seldom before the 10th or after the 50th year, but occasionally chondrosarcoma was reported in childhood [ 27 ].

In our series the 60% of patient were aged from 20 to 40 years, slightly less than reported in some studies in literature [ 19 ]. In addition, 32 cases were younger than 30 years and almost the 7% of the cases were younger than 20 years. Even if the median age is in line with medical literature, the present series highlighted the presence of younger patient affected by secondary peripheral chondrosarcoma, particularly because some of these cases are grade 2 SPC. This finding highlights the need of a personalization of follow-up management for young borderline cases.

The higher prevalence of males in this series is in line with literature [ 13 ]. This is according to a more severe disease in male patients, moreover in Pedrini and colleagues’ study [ 17 ] an almost equal sex ratio was reported in contrast to a recent review [ 19 ] and a significant trend toward a more severe phenotype in males was described [ 1 ].

According to literature, the most common sites were pelvis and proximal femur, even if in this series we observed scapula involvement in only 5% versus 12% reported in medical literature and spine was the site of malignant transformation in 6% of cases versus 8.6% in the literature review [ 19 ]. Pelvis, lower limb, and spine account up to 80% of the cases in the present study, in line with literature data [ 19 ]. The higher risk of malignant transformation at the pelvis can be related to its anatomical complexity and adjacency to neurovascular and visceral bundles as per literature [ 28 ] In addition, the first suspect for malignant transformation is the increase of size of an OC; if this lesion is in a deep site, only imaging studies can show this variation, so pelvis, more than any other bone district, can allow the tumor can grow before detection.

In literature, cap thickness is a factor capable to differentiate benign osteochondromas versus chondrosarcomas [ 9 ]. In our study, the measurement of cap thickness and the disease severity did not result as statistically related, considering the availability of data was for 69 cases.

Instead, in the present study, the higher histological grade (≥ 2) and the partial resection were confirmed to have a prognostic value: both related to worse course of the disease with lower DFS (recurrence/MTS free survival). This data is in line with previous studies, focused on chondrosarcoma, that revealed histologic grade and surgery as two important disease prognostic factors [ 29 , 30 ].

The disease progression in terms of local recurrence or metastasis was described in about the 20% of the cases, according to a reported survival rate in secondary chondrosarcoma of 75% in a large Mayo Clinic study, even if not focused on MO [ 11 ].

Some reports described a more severe phenotype and a higher risk of malignant transformation in EXT1 variant carriers [ 2 , 31 , 32 , 33 , 34 ], but this finding has not been confirmed in other large series [ 17 ]. In the present study, EXT1/EXT2 genotype was known in less than half of the patients, so it is not possible to infer if the carriers of pathological variants in EXT1 had actually an increased risk to malignant transformation or other genotype-phenotype correlation. In 6 patients with recurrence of the disease, molecular analysis was available and about equal distribution of variants on EXT1 and EXT2 genes was observed.

These data confirm that SPC in MO patients is an impacting complication, particularly in male, and suggest that malignant transformation can occur also in younger patient, in a not irrelevant number of cases. In addition, our data highlight that OCs more frequently undergo to malignant transformation in some sites, like pelvis and complete resection is the most common surgical treatment. Moreover, our results show that a worse course of the disease is associated with higher histological grade. In conclusion, that knowledge is crucial to better define the optimal screening type for MO patients, nevertheless further studies will be recommended.

Data availability

The data supporting the conclusions of this manuscript will be made available by the corresponding authors on a reasonable request. The data are not publicly available due to national privacy regulations.

Abbreviations

Disease-Free Survival

Hazard Ratio

Hematoxylin and Eosin

Interquartile Range

Multiple Ligation-dependent Probe Amplification

Multiple Osteochondromas

Osteochondromas

Registry of Multiple Osteochondromas

Secondary Peripheral Chondrosarcoma

World Health Organization

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Acknowledgements

Eleven authors of this publication are members of the European Reference Network for rare BONe Diseases (ERN BOND), https://ernbond.eu/ .

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Maria Gnoli, Morena Tremosini, Evelise Brizola, Marina Mordenti, Manila Boarini, Manuela Locatelli, Elena Pedrini & Luca Sangiorgi

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MGn designed the study and prepared the first draft of the paper. She had the main role in revising process for the final draft. She was also involved in the patients’ recruitment, revision, and organization of all clinical data. MGa and AR revised the stained sections, contributed to clinical diagnosis, and participated to the draft of the paper. ES contributed to clinical diagnosis and was involved in patients’ recruitment, data revision and in paper drafting. AE performed all statistical analyses and participated to manuscript drafting. MT contributed to data collection and draft of the manuscript. EB contributed to clinical diagnosis, data collection and manuscript drafting. MM contributed to data collection and interpretation, support the drafting, reviewing, and editing of the manuscript. MB performed data collection, cleaning, and interpretation. She participated in drafting and in critical revision of the manuscript. ML performed data collection and interpretation and participated to all the steps of drafting process. EP performed all molecular analyses, assessed the interpretation of the resulting variants, and participated to all the steps of drafting process. LS supported the study design and participated to the drafting and revision of the manuscript. All authors revised the paper critically for intellectual content and then approved the final version. All authors agree to be accountable for the work and to ensure the accuracy and integrity of the paper.

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Gnoli, M., Gambarotti, M., Righi, A. et al. Secondary peripheral chondrosarcoma in multiple osteochondromas: a retrospective single-institution case series. Orphanet J Rare Dis 19 , 63 (2024). https://doi.org/10.1186/s13023-023-03006-8

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  • Secondary peripheral chondrosarcoma
  • Malignant degeneration
  • Multiple osteochondromas
  • Rare skeletal disorders
  • Histological evaluation

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literature review vs case study

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How to identify juxtaglomerular cell tumor by ultrasound: a case series and review of the literature

  • Li Wang 1 , 2   na1 ,
  • Meiying Li 1   na1 ,
  • Siqi Jin 1 ,
  • Yunshu Ouyang 1 ,
  • Fenglan Wang 2 ,
  • Jianchu Li 1 ,
  • Yuxin Jiang 1 ,
  • He Liu 1 &
  • Qingli Zhu 1  

BMC Medical Imaging volume  24 , Article number:  46 ( 2024 ) Cite this article

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Metrics details

To study the value of ultrasound in the diagnosis of juxtaglomerular cell tumor (JGCT).

From January 2005 to July 2020, fifteen patients diagnosed as JGCT by surgical pathology in Peking Union Medical College Hospital were collected. All patients underwent preoperative ultrasound examination. The clinical, laboratory, ultrasound, computed tomography (CT), surgical, and pathological features of the patients were analyzed retrospectively.

The 15 patients were 5 males and 10 females with a median age of 29 years (10 ∼ 72 years). 14 of them had hypertension and one had normal blood pressure. The tumors were all solitary, with a median diameter of 1.5 cm (0.9–5.9 cm). Among the fifteen patients, eleven were correctly detected by preoperative ultrasound, and four were missed. There was a significant difference in tumor size (2.64 ± 1.48 cm vs. 1.23 ± 0.21 cm) and whether the tumor protruded outward (9/11 vs. 0/4) between the ultrasound-detected group and the ultrasound-missed group ( p  = 0.010, p  = 0.011). Of the 11 tumors detected by ultrasound, four were extremely hypoechoic, two were hypoechoic, three were isoechoic, and two were hyperechoic. Color Doppler showed no blood flow in five tumors with the size range from 0.9 to 2.0 cm, and mild blood flow in six tumors with the size range from 2.8 to 5.9 cm.

Conclusions

JGCT is rare, and has characteristic clinical manifestations. Diagnosis should be suspected in case of secondary hypertension, particularly in young women, if no renal vascular cause was found. Ultrasound, combined with clinical manifestations, was helpful for the diagnosis.

Peer Review reports

Introduction

JGCT is a rare and benign renal tumor that originate from the juxtaglomerular cells of the capillary adventitia in the juxtaglomerular complex. The tumor is also called reninoma because it can secrete renin [ 1 , 2 ]. Since the first report of JGCT in 1967 [ 3 ], fewer than 200 cases have been reported in the literature [ 4 ]. It is more common in young females aged 20–39 years, with a male: female ratio of 1:2 [ 5 ]. Occasionally cases in children and elderly patients were reported [ 2 , 6 , 7 ]. Typical clinical manifestations are hypertension, high renin activity, secondary aldosteronism, and hypokalemia [ 8 ], but some patients may have atypical clinical manifestations. Surgery is an effective treatment for JGCT [ 9 , 10 , 11 ].

Improvements in imaging techniques have led to a shorter interval between the occurrence of hypertension and the diagnosis of JGCT [ 12 ]. However, the diagnosis of JGCT remains challenging because it is rare, generally small, located in the renal cortex or subcortical regions, and may be missed or misdiagnosed [ 5 ]. Ultrasound could be helpful, however, the ultrasound manifestations of JGCT have not been fully studied. This study retrospectively summarized the clinical, laboratory, ultrasound and computed tomography (CT) characteristics of 15 JGCT patients and reviewed the literature to study the value of ultrasound in the diagnosis of JGCT.

This study was approved by the institutional review board of our hospital. From January 2005 to July 2020, fifteen patients diagnosed as JGCT by surgical pathology in Peking Union Medical College Hospital were collected. The clinical, laboratory, ultrasound, CT, surgical, and pathological features of the patients were analyzed retrospectively.

Ultrasound examination

The ultrasound examination was performed by the PHLIPS HDI 5000, PHILIPS IU 22 machine (Philips Healthcare, Amsterdam, Netherland) and GE LOGIQ 9 (GE Healthcare, Wauwatosa, WI), equipped with 3.5–5 MHz probe, kidney presets. The grayscale and Color Doppler images of each patient were acquired and saved by radiologists with more than 5 years of experience in ultrasound examination. Image analysis was carried out by two radiologists with more than 5 years of experience with no knowledge of any clinical information. In case of disagreement between the two radiologists, the consensus was reached by discussion.

Image analysis included the location of the tumor (right/left kidney, cortex/cortex and medulla, protruded outward or not), size (the longest diameter), echo pattern (hypoechoic/isoechoic/ hyperechoic), shape (regular/irregular), margin (clear/indistinct), capsule (existent/ inexistent), blood flow signal (no/mild/abundant). Compared with the adjacent renal cortex, the echo pattern is divided into hypoechoic, isoechoic, and hyperechoic. The shape is classified as regular (round or lobulated), and irregular [ 13 ]. Clear margin meant that the tumor had a clear demarcation with the surrounding tissues. Otherwise, the margin was defined as indistinct. The capsule referred to the fibrous connective tissue membrane around the tumor, which appeared as a hyperechoic line on ultrasound. The blood flow was classified as no, mild (1–2 blood flows), and abundant (≥ 3 blood flows) according to Adler’s grading [ 14 ].

Surgery and histopathological examinations

Surgeries were performed after the completion of necessary examinations. The location and size of the tumors were recorded during surgeries. Histopathological results were considered as the golden standard.

Literature review

The literature search was conducted in Pub Medline and Embase with the keyword string “juxtaglomerular cell tumor ultrasound”. The study inclusion criteria included the diagnosis of JGCT with ultrasound descriptions (at least size and echo). The exclusion criteria were review articles, irrelevant or duplicate papers, and papers without full text available.

Statistical analysis

SPSS 20.0 software was used for statistical analysis. Shapiro-wilk test was used to determine the normality of the data. Independent-samples T test or Fisher’s exact test was used to compare the differences between the two groups. P-values < 0.05 were considered statistically significant.

Baseline characteristics

The clinical, ultrasound, and CT manifestations of 15 patients with JGCT were shown in Table  1 . Among the 15 patients, there were 5 males and 10 females with a median age of 29 years (min-max, 10–72 years). Eleven (73.3%, 11/15) patients had grade III hypertension, three (20.0%, 3/15) patients had grade II hypertension, and one (6.7%, 1/15) patient had normal blood pressure. Six patients had blurred vision, six had dizziness or headache, and one had cerebral hemorrhage. The median interval from the diagnosis of hypertension to JGCT was 27 months (min-max, 1 month-12 years). Serum potassium was low in 10 patients (median 2.75 mmol/L, min-max, 2.3–3.2 mmol/L), and normal in 5 patients. The renin activity test was conducted in nine patients, and the results all showed high activity (median 6.17 ng/ml/h, min-max, 3.07–17.6 ng/ml/h). Plasma renin was tested in three patients, two of whom showed high levels (859 µIU/ml, 583 pg/ml) and one normal. The aldosterone test was performed in eleven patients, yielding ten elevated results (median: 348.95 pg/ml, min-max, 164.7–967 pg/ml) and one normal. Three patients were hospitalized for renal tumor surgery with no blood tests for reninoma, two of them had hypertension, and one had normal blood pressure. The serum potassium was normal in these three patients.

All 15 JGCTs were solitary tumors, including seven in the right kidney and eight in the left kidney. The median longest diameter of the tumors was 1.5 cm (min-max, 0.9–5.9 cm).

Ultrasound manifestations

Among the 15 JGCTs, 11 were correctly detected by preoperative ultrasound, and 4 were missed.

Of the 11 tumors detected by ultrasound, the median longest diameter of the tumors was 2.8 cm (min-max, 0.9–5.9 cm). Nine protruded outward, one protruded toward the collecting system, and one was completely in the renal cortex with no protrusion. Four were extremely hypoechoic (Fig.  1 ), two were hypoechoic, three were isoechoic (Fig.  2 ), and two were hyperechoic. The morphology was regular in ten cases and irregular in one case. The margin was clear in eight cases and indistinct in three cases. Ultrasound showed a capsule in two cases and no capsule in nine cases. Color Doppler showed no blood flow in five tumors with the size range from 0.9 to 2.0 cm, and mild blood flow in six tumors with the size range from 2.8 to 5.9 cm. The preoperative diagnosis was one reninoma, one renal cell carcinoma, and nine undetermined tumors.

figure 1

A JGCT lesion in the right kidney. Ultrasound showed extremely hypoechoic lesion (arrow), 1.2 × 1.0 × 0.8 cm,with regular morphology and clear boundary

figure 2

A JGCT lesion in the left kidney. (a) Grayscale ultrasound showed isoechoic lesion (arrow), 4.0 × 3.4 × 3.1 cm, with regular morphology and clear boundary. (b) Color Doppler ultrasound showed mild blood flow. (c) Morphologic features on hematoxylin-eosin stain. The diagnosis of JGCT was confirmed by the postoperative pathology

Of the 4 tumors missed by ultrasound, the longest diameter was 1.0 cm, 1.2 cm, 1.5 cm, and 1.2 cm respectively. All of them located in the renal cortex with no protrusion outward.

There was a significant difference in tumor size (2.64 ± 1.48 cm vs. 1.23 ± 0.21 cm, Independent-samples T test, p  = 0.010) between the ultrasound-detected group and ultrasound-missed group. There was also a significant difference in whether the tumor protruded outward (9/11 vs. 0/4, Fisher’s exact test, p  = 0.011) between the two groups (Table  2 ).

CT manifestations

Of the 11 tumors detected by ultrasound, non-contrast enhanced CT showed five low density, three isodensity, one slightly high density and two mixed density. Dynamic contrast-enhanced CT showed nine mild enhancement, and two moderate enhancement in parenchymal phase. The preoperative CT diagnosis was three reninoma, one renal cell carcinoma, and seven undetermined tumors.

Of the 4 lesions missed by ultrasound, two tumors located in the cortex, with the size of 1.0 and 1.2 cm respectively, showed similar density with the cortex on non-contrast enhanced CT and mild enhancement during parenchymal phase on contrast enhanced CT. One tumor located in the cortex with the size of 1.2 cm, showed slightly high density on non-contrast enhanced CT and mild enhancement during parenchymal phase on contrast enhanced CT. One tumor located in the cortex and medulla, with the size of 1.5 cm, showed slightly high density on non-contrast enhanced CT and moderate enhancement during parenchymal phase on contrast enhanced CT. The preoperative CT diagnosis was three reninoma, and one renal cell carcinoma.

Surgery and follow-up

All 15 patients underwent partial nephrectomy. Two of them underwent intraoperative ultrasound localization, which successfully guided the laparoscopic partial nephrectomy. The blood pressure returned to normal in 13 patients after operation. No tumor relapse was found in any of the 15 patients during the follow-up of 6 months to 15 years.

Eighty-five papers (65 papers in PubMed and 20 papers in Embase) were retrieved. A total of 25 patients in 13 papers met the inclusion criteria including 17 females and 8 males with a median age of 24 years (11–57 years) [ 4 , 11 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ]. All tumors were solitary, with a median size of 3.3 cm (0.6–6.5 cm). Two JGCTs were extremely hypoechoic, 12 were hypoechoic, 1 were isoechoic, 10 were hyperechoic.

JGCT is a rare renal tumor. Haab et al. reported eight cases of JGCT among 30,000 hypertensive patients in a 15-year period [ 26 ]. The tumor is usually solitary, small in size (< 3 cm, rarely > 4 cm) [ 1 , 5 ]. Surgery is an effective treatment. To our knowledge, this is the largest report describing the clinical, laboratory, ultrasound and CT manifestations of JGCT, providing detailed descriptions of the ultrasound characteristics of 15 cases.

In our series, JGCT showed extremely hypoechoic, hypoechoic, isoechoic or hyperechoic, with no or mild blood flow, as described previously [ 4 , 5 , 6 , 7 , 8 , 10 , 11 , 19 , 20 , 22 , 23 , 25 , 26 , 27 , 28 , 29 ]. Hypoechoic, especially extremely hypoechoic, may be explained by the closely packed cellular, highly organized, and compact architectural organization, as seen in other endocrine tumors. Extremely hypoechoic might be the characteristics, however, the data remained insufficient and further study is needed. The tumor showed no or mild blood flow might be related to the vasoconstriction caused by renin and the decreased blood flow caused by the proliferation of intima and middle layer of tumor arterioles [ 29 ]. Pathologically, JGCT generally has fibrous capsule [ 11 , 22 , 28 ], however we observed capsule in only two patients, which might be due to the thin capsule hardly detected by ultrasound.

The ultrasound diagnosis of JGCT is still challenging. In our study, four tumors, with small size (1.0 ∼ 1.5 cm) and located completely in the cortex with no protrusion, were missed by ultrasound. Two of them showed similar density with the cortex and were missed on the non-contrast enhanced CT. Because ultrasound and non-enhanced CT can fail, contrast enhanced CT should be performed when a JGCT is suspected. The contrast enhanced CT was positive in all of the 15 JGCTs in our study, as well as in the cases reported [ 5 , 26 , 30 , 31 , 32 ]. Taken together, contrast enhanced CT should be considered in all cases of JGCT. Contrast enhanced ultrasound might be helpful [ 4 , 25 ]. Li et al. reported two cases of JGCT, invisible by previous conventional ultrasound, found by contrast enhanced ultrasound. They were complete endophytic, and showed hypoenhancement, slow wash in and slow wash out. One was 1.0 × 1.0 × 0.7 cm, the other was 3.0 × 2.0 × 1.0 cm [ 25 ]. The small sample size precluded a firm recommendation of contrast enhanced ultrasound for JGCT diagnosis. JGCT may have specific features in enhanced ultrasound, which needs to be confirmed by future studies. However, the application of enhanced ultrasound needs to be based on the two-dimensional ultrasound localization of the lesion. Therefore, enhanced ultrasound may not be helpful in reducing ultrasound misdiagnosis of JGCT cell tumors, which requires other solutions.

The limitation of our study was the small number of cases and techniques such as contrast enhanced ultrasound was not applied. Most of the studies were case reports, so we did not conduct a meta-analysis. A multicenter study and more in-depth prospective studies should be conducted in the future to provide a more comprehensive information of this rare tumor.

JGCT is rare, and has characteristic clinical manifestations. Diagnosis should be suspected in case of secondary hypertension, particularly in young women, if no renal vascular cause is found. Ultrasound, combined with clinical manifestations, was helpful for the diagnosis.

Data availability

The data and material can be provided if asked on a basis of good reasons.

Abbreviations

juxtaglomerular cell tumor

computed tomography

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Li Wang and Meiying Li contributed equally to this work.

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Department of Ultrasound, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Shuaifuyuan 1, Dongcheng District, 100730, Beijing, China

Li Wang, Meiying Li, Siqi Jin, Yunshu Ouyang, Ke Lv, Jianchu Li, Yuxin Jiang, He Liu & Qingli Zhu

Department of Ultrasound, Tangshan Central Hospital, West of Youyi Road, Lubei District, 063000, Tangshan City, Hebei, China

Li Wang & Fenglan Wang

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Correspondence: [email protected] and [email protected]. Joint corresponding authors: HL and QZ. LW and ML have contributed equally. All authors have contributed significantly to this paper. LW and ML collected and analyzed the data, then wrote the manuscript; SJ, YO, FW, and KL provided professional opinions about JGCT and ultrasound manifestations; JL and YJ revised the manuscript; HL and QZ designed and supervised the study. All authors read and approved the final manuscript.

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Correspondence to He Liu or Qingli Zhu .

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The study was conducted in accordance with the Declaration of Helsinki. The Institutional Review Board of Peking Union Medical College Hospital has reviewed the protocol of this manuscript and determined that this study is a retrospective study and the need for informed consent is waived.

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Wang, L., Li, M., Jin, S. et al. How to identify juxtaglomerular cell tumor by ultrasound: a case series and review of the literature. BMC Med Imaging 24 , 46 (2024). https://doi.org/10.1186/s12880-024-01220-9

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