Immunochemistry in the work-up of mesothelioma and its differential diagnosis and mimickers

Our plain-English summary of Immunochemistry in the work-up of mesothelioma and its differential diagnosis and mimickers, by W.S. Mneimneh, Y. Jiang, A. Harbhajanka, et al (Diagnostic Cytopathology, 2021).

The study

• Authors: W.S. Mneimneh, Y. Jiang, A. Harbhajanka, C.W. Michael
• Journal: Diagnostic Cytopathology
• Published: 2021;49(5):582-595
• Type of article: Review
• Cited by: 12 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The differential diagnosis in cellular effusions with cytological atypia often includes malignant mesothelioma (MM), reactive mesothelial proliferation, and malignancies of metastatic origin, particularly carcinomas. The International Reporting System for Serous Fluid recently established guidelines for reporting MM. In conjunction with the cytomorphologic evaluation, the role of immunochemistry (IC) was emphasized as a very useful tool in the workup of serous fluids, especially with the availability of novel markers. Utilizing a panel of markers, IC allows the characterization of the cells, whether mesothelial or not, and when mesothelial origin is established, IC can frequently assist in delineating its benign or malignant nature. IC can also confirm metastatic disease, allowing the identification of the primary origin in most cases. This review summarizes the current status of IC and its role in the diagnosis of MM and its differential diagnosis in serous fluids.

© 2021 Wiley Periodicals LLC.

In plain English

This article was a review, not a new study. The authors summarized published research on immunochemistry (antibody staining of cells) for diagnosing malignant mesothelioma, mainly the epithelioid type, in samples of body-cavity fluid (serous effusions). It covered markers showing that cells are mesothelial, markers separating mesothelioma from reactive (benign) mesothelial cells, and markers pointing to metastatic carcinoma instead. The review cited figures from earlier studies. Calretinin had a sensitivity of 81% to 100% for detecting mesothelioma in effusion specimens. Loss of BAP1 staining was seen in 27%-57% of mesotheliomas but in none of the reactive mesothelial cell samples. Using BAP1 and MTAP staining together reportedly detected mesothelioma with 78% sensitivity, higher than BAP1 alone. Desmin was expressed in 84%-92% of reactive cases and 0%-6% of mesotheliomas. Claudin-4 had 85%-99% sensitivity and 100% specificity for telling carcinoma from mesothelioma. The authors noted that guidelines recommend at least two mesothelial and two non-mesothelial markers. They stated that no single marker is entirely specific and concluded that each antibody must be read within a panel.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Review of published literature on immunochemistry in effusion cytology; no new data were collected
• Who was studied: No study population of its own; the review drew on published studies of serous (body-cavity) fluid samples with malignant mesothelioma, reactive mesothelial cells, or metastatic carcinoma
• Main results:
  • As reported in the reviewed literature, calretinin had a sensitivity of 81% to 100% for detecting malignant mesothelioma in effusion specimens
  • As reported in the reviewed literature, nuclear WT1 staining was found in more than 90% of mesothelioma effusion specimens and in 20%-23% of metastatic adenocarcinomas
  • As reported in the reviewed literature, BAP1 staining was lost in 27%-57% of mesotheliomas and in none of the reactive mesothelial cell samples
  • As reported in the reviewed literature, using MTAP and BAP1 staining together detected mesothelioma with 78% sensitivity, higher than BAP1 alone
  • As reported in the reviewed literature, desmin was expressed in 84%-92% of reactive mesothelial cell cases in effusions and in 0%-6% of mesothelioma cases
  • As reported in the reviewed literature, claudin-4 had a sensitivity of 85%-99% and a specificity of 100% in distinguishing carcinoma from mesothelioma
  • In one cited study, the newer marker HEG1 was positive in all 41 of 41 mesotheliomas and negative in carcinomas other than ovarian carcinomas
  • The authors noted that the guidelines recommend at least two mesothelial and two non-mesothelial markers
  • The authors stated that no single marker is entirely specific or universal
• The authors' conclusion: The authors concluded that the result of any single antibody should be interpreted within the context of the selected panel and never on its own
• Limitations the authors state:
  • The authors stated that a detailed discussion of technical issues of immunochemistry was outside the scope of the article
  • The authors stated that experience with HEG1 is limited and that more studies are needed

Topics

The National Library of Medicine indexes this study under subjects our site covers: Mesothelioma.

Medical terms in this study, explained in our Lexicon: Mesothelioma, Differential Diagnosis, Malignant Mesothelioma, Carcinoma, Serous Fluid.

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• Utility of BAP1 Immunohistochemistry and p16 (CDKN2A) FISH in the Diagnosis of Malignant Mesothelioma in Effusion Cytology Specimens — H.C. Hwang, B.S. Sheffield, et al. (2016)
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