Guidelines for the cytopathologic diagnosis of epithelioid and mixed-type malignant mesothelioma: Complementary Statement from the International Mesothelioma Interest Group, Also Endorsed by the International Academy of Cytology and the Papanicolaou Society of Cytopathology

Our plain-English summary of Guidelines for the cytopathologic diagnosis of epithelioid and mixed-type malignant mesothelioma: Complementary Statement from the International Mesothelioma Interest Group, Also Endorsed by the International Academy of Cytology and the Papanicolaou Society of Cytopathology, by A. Hjerpe, V. Ascoli, C.W. Bedrossian, et al (Diagnostic Cytopathology, 2015).

The study

• Authors: A. Hjerpe, V. Ascoli, C.W. Bedrossian, M.E. Boon, J. Creaney, B. Davidson, A. Dejmek, K. Dobra, A. Fassina, A. Field, P. Firat, T. Kamei, T. Kobayashi, C.W. Michael, S. Önder, A. Segal, P. Vielh, International Mesothelioma Interest Group, International Academy of Cytology
• Journal: Diagnostic Cytopathology
• Published: 2015;43(7):563-76
• Cited by: 23 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: To provide practical guidelines for the cytopathologic diagnosis of malignant mesothelioma.

Data Sources: Cytopathologists with an interest in the field involved in the International Mesothelioma Interest Group (IMIG) and the International Academy of Cytology (IAC) contributed to this update. Reference material includes peer-reviewed publications and textbooks.

Rationale: This article is the result of discussions during and after the IMIG 2012 conference in Boston, followed by thorough discussions during the 2013 IAC meeting in Paris. Additional contributions have been obtained from cytopathologists and scientists who could not attend these meetings, with final discussions and input during the IMIG 2014 conference in Cape Town.

© 2015 Wiley Periodicals, Inc.

In plain English

This article was a consensus guideline written by cytopathologists, not a study of patients. It came out of discussions in the International Mesothelioma Interest Group and the International Academy of Cytology at meetings in Boston (2012), Paris (2013) and Cape Town (2014). It set out how malignant mesothelioma can be diagnosed from cells in fluid (an effusion) collected from the pleural or peritoneal cavity. The authors recommended that every case be confirmed with antibody staining, using a panel of at least four antibodies: two that favor mesothelioma and two that argue against it. They described optional tests, including fluid hyaluronan and mesothelin levels, electron microscopy and a genetic test called FISH. They stated that a history of asbestos exposure is not required for the diagnosis. Citing an earlier audit, they wrote that effusion cytology with appropriate ancillary techniques can diagnose mesothelioma with a positive predictive value of 100%. The authors concluded that accuracy is unquestioned when the guidelines are followed. They noted that the diagnosis of sarcomatoid mesothelioma can rarely be made from effusion cytology, and that a negative result does not rule mesothelioma out.

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: Consensus guideline (expert opinion statement), not an original study of patients
• Who was studied: No patients were studied. The authors were cytopathologists and scientists from the International Mesothelioma Interest Group (IMIG) and the International Academy of Cytology (IAC). The guideline came from discussions at the IMIG 2012 conference in Boston and the 2013 IAC meeting in Paris, with final input at IMIG 2014 in Cape Town.
• Exposure: Exposure was not studied. The authors stated that a history of asbestos exposure can reinforce suspicion of malignant mesothelioma but is not mandatory for the diagnosis.
• Main results:
  • The authors strongly recommended that every cytological diagnosis of malignant mesothelioma be confirmed with immunocytochemistry or immunohistochemistry (antibody staining).
  • They recommended a panel of at least four antibodies, two in favor of and two against mesothelioma. They stated that the diagnosis should never rest on a single staining reaction.
  • For the optional fluid test, the two-step section states that hyaluronan concentrations above 250 mg/l indicate mesothelioma and that samples with 60 to 249 mg/l can be tested for mesothelin. The authors stated that such high hyaluronan levels are found in only 50 to 60% of mesothelioma effusions.
  • The authors stated that electron microscopy can give a conclusive mesothelioma diagnosis in only about 50% of cases.
  • The authors stated that loss of the 9p21 chromosome band on FISH testing supports a mesothelioma diagnosis but does not by itself establish it (it is not pathognomonic).
  • Citing an earlier study (reference 5, a 20-year audit by Segal and colleagues), the authors stated that examining an effusion using cytology with appropriate ancillary techniques can diagnose mesothelioma with a positive predictive value of 100%. This figure comes from that earlier study, not from this article.
• The authors' conclusion: The authors concluded that the sensitivity of cytology may vary with the experience of the cytopathologist, but that its accuracy is unquestioned when these guidelines are followed.
• Limitations the authors state:
  • The diagnosis of sarcomatoid mesothelioma can rarely be established by effusion cytology. Elsewhere the authors wrote that almost all sarcomatoid and desmoplastic cases cannot be diagnosed this way.
  • Effusions heavily mixed with blood and inflammatory cells make the diagnosis difficult.
  • A negative cytology result does not rule out mesothelioma.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Lung cancer, Mesothelioma, Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Epithelioid, Malignant Mesothelioma, Mesothelioma, Cytology, Cytopathology, IMIG.

Related studies

• Guidelines for the cytopathologic diagnosis of epithelioid and mixed-type malignant mesothelioma. Complementary statement from the International Mesothelioma Interest Group, also endorsed by the International Academy of Cytology and the Papanicolaou Society of Cytopathology — A. Hjerpe, V. Ascoli, et al. (2015)
• Guidelines for the cytopathologic diagnosis of epithelioid and mixed-type malignant mesothelioma: Complementary statement from the international mesothelioma interest group, also endorsed by the international academy of cytology and the papanicolaou society of cytopathology. A proposal to be applauded and promoted but which requires updating — M. Sheaff (2020)
• Guidelines for the Cytopathologic Diagnosis of Epithelioid and Mixed-Type Malignant Mesothelioma: a secondary publication — A. Hjerpe, V. Ascoli, et al. (2015)
• Cytopathologic Diagnosis of Epithelioid and Mixed-Type Malignant Mesothelioma: Ten Years of Clinical Experience in Relation to International Guidelines — A. Hjerpe, S. Abd-Own, et al. (2018)
• Comments on the recently published "Guidelines for the cytopathologic diagnosis of epithelioid and mixed-type malignant mesothelioma" — A. Hjerpe, K. Dobra (2015)
• Guidelines for Pathologic Diagnosis of Malignant Mesothelioma 2017 Update of the Consensus Statement From the International Mesothelioma Interest Group — A.N. Husain, T.V. Colby, et al. (2018)

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