Guidelines for the Cytopathologic Diagnosis of Epithelioid and Mixed-Type Malignant Mesothelioma: a secondary publication

Our plain-English summary of Guidelines for the Cytopathologic Diagnosis of Epithelioid and Mixed-Type Malignant Mesothelioma: a secondary publication, by A. Hjerpe, V. Ascoli, C.W. Bedrossian, et al (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
• Journal: Cytopathology
• Published: 2015;26(3):142-56
• Type of article: Guideline
• Cited by: 21 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 John Wiley & Sons Ltd.

In plain English

This article was a set of consensus guidelines, not a new study. It was written by cytopathologists linked to the International Mesothelioma Interest Group and the International Academy of Cytology, and it reprinted an article first published in Acta Cytologica. It described how malignant mesothelioma, mainly the epithelioid and mixed types, can be diagnosed from fluid (effusion) samples using cell appearance plus additional tests. The authors recommended never relying on a single antibody stain. For fluid hyaluronan, they stated that levels above 250 mg/l indicate mesothelioma but are reached in only 50–60% of mesothelioma effusions. They stated that electron microscopy gives a conclusive diagnosis in some 50% of cases, and that sarcomatoid mesothelioma can rarely be diagnosed from fluid. They wrote that a history of asbestos exposure is not required for the diagnosis, and that in most countries such diagnoses are accepted in medical practice and in courts. The authors concluded that accuracy is unquestioned when the guidelines are followed, while sensitivity may vary with the cytopathologist's experience.

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 / review (secondary publication of an article first published in Acta Cytologica 2015;59:2-16), based on expert discussion and published literature
• Who was studied: No patients were studied. The guidelines were developed by cytopathologists involved in the International Mesothelioma Interest Group (IMIG) and the International Academy of Cytology (IAC). They cover effusion cytology of epithelioid and mixed-type malignant mesothelioma, including pleural, peritoneal and pericardial disease.
• Exposure: No exposure was studied. The authors stated that a history of asbestos exposure supports suspicion of mesothelioma but is not required for the diagnosis.
• Main results:
  • The authors recommended that the diagnosis never rest on a single immunocytochemistry or immunohistochemistry stain. They recommended a panel of at least four antibodies, two in favour of mesothelioma and two against it.
  • As a suggested panel, the authors stated that EMA (membranous pattern) and calretinin positive, with CEA and BerEp4 negative, is the typical pattern for mesothelioma in most cases.
  • To separate mesothelioma from reactive (benign) mesothelial cells, the authors described loss of desmin reactivity as a commonly recommended criterion for mesothelioma.
  • The authors stated that hyaluronan concentrations in the effusion above 250 mg/l indicate mesothelioma, and that samples with 60–249 mg/l can be tested further for mesothelin.
  • The authors stated that such high hyaluronan levels are found in only 50–60% of mesothelioma effusions.
  • The authors stated that mesothelin is not entirely specific for mesothelioma, because carcinomas, particularly ovarian and pancreatic carcinomas, can also produce it.
  • The authors stated that electron microscopy can give a conclusive mesothelioma diagnosis in only some 50% of cases.
  • The authors stated that a homozygous deletion of the 9p21 band found by FISH supports a diagnosis of mesothelioma but is not pathognomonic (not on its own definitive).
  • The authors stated that, in most countries, a definitive diagnosis of mesothelioma made from cytology plus ancillary tests is accepted in everyday medical practice and in courts of law.
• The authors' conclusion: The authors concluded that, although sensitivity may vary with experience, the accuracy of cytology for diagnosing mesothelioma is unquestioned when these guidelines are followed.
• Limitations the authors state:
  • The sensitivity of cytology may vary with the experience of the cytopathologist.
  • A negative cytology finding does not rule out mesothelioma.
  • Sarcomatoid ('nonepithelioid') mesothelioma is not detected by this approach.
  • Effusions heavily mixed with blood and inflammatory cells make the diagnosis difficult.
  • Most diagnostic methods have been validated on pleural effusions, not on fluid from other body cavities.

Topics

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

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

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. 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 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)
• Metastatic proximal epithelioid sarcoma in pleural effusion: cytopathologic findings and differential diagnosis — H. Guan, F. Haque, et al. (2013)

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