The diagnosis of malignant mesothelioma in effusion cytology: a reappraisal and results of a multi-institution survey

Our plain-English summary of The diagnosis of malignant mesothelioma in effusion cytology: a reappraisal and results of a multi-institution survey, by A. Paintal, K. Raparia, M.F. Zakowski, et al (Cancer Cytopathology, 2013).

The study

• Authors: A. Paintal, K. Raparia, M.F. Zakowski, R. Nayar
• Journal: Cancer Cytopathology
• Published: 2013;121(12):703-7
• Cited by: 42 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: The diagnosis of malignant mesothelioma (MM) in effusion specimens is controversial. At the study institution (Northwestern University), a primary diagnosis of MM is made on fluid cytology specimens. In an effort to estimate the practice at other institutions, a survey was disseminated regarding cytologic diagnosis of MM. The authors also evaluated their own institution's experience with primary cytologic diagnosis of MM.

Methods: Patients with MM at the study institution were identified from 1992 through 2011. Fluid cytology specimens preceding histologic diagnoses were reviewed. A survey was sent to a number of cytology laboratories to assess practice patterns regarding the diagnosis of MM.

Results: At the study institution, 20 cases of MM had effusion specimens preceding the diagnostic histologic material. In 6 cases (30%), a definitive diagnosis of MM was rendered via cytology alone. There were no false-positive diagnoses of MM. Of 55 laboratories that responded to the survey, 36 reported making a definitive diagnosis of MM after cytologic analysis. Almost all laboratories (35) willing to diagnose MM in effusions reported performing immunohistochemistry to distinguish adenocarcinoma from MM. A smaller proportion (18) of these laboratories reported doing additional immunohistochemistry or fluorescence in situ hybridization for p16 to help distinguish benign from malignant mesothelial proliferations. Those who do not definitively diagnose MM in fluid specimens state inability to identify invasion and overlap with reactive mesothelial proliferation as factors supporting their practice. Most respondents (32) felt that the clinicians at their institution would manage a patient based on a cytologic diagnosis of MM.

Conclusions: The majority of respondents reported making a definitive diagnosis of MM in effusion cytology specimens. The diagnosis of MM in effusions, although not sensitive, is extremely specific.

© 2013 American Cancer Society.

In plain English

This article combined an online survey of cytology laboratories with a review of the authors' own hospital cases. It asked whether malignant mesothelioma can be definitively diagnosed from fluid (effusion) samples rather than from tissue. Of 68 institutions invited, 55 responded, most of them academic medical centers. In the survey table, 36 of 55 respondents (65%) said they make a definitive diagnosis of mesothelioma on cytology specimens; the text elsewhere gives 35 (63%). Of 51 respondents, 32 (63%) felt their clinicians would manage a patient on a cytologic diagnosis. At Northwestern Memorial Hospital in Chicago, 20 patients with tissue-confirmed pleural or peritoneal mesothelioma had a fluid sample within the 3 months before confirmation. Of these, 6 (30%) had been called positive for mesothelioma, and there were no false-positive mesothelioma diagnoses. The authors concluded that most respondents will diagnose mesothelioma in effusions. They considered this practice supported by literature showing excellent specificity in the appropriate clinical setting and with supporting additional tests. They noted low sensitivity and no reliable way to tell tumor subtypes apart on cytology. The article does not discuss asbestos.

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: Internet-based survey of pathologists at cytology laboratories, plus a retrospective review of the authors' own institution's effusion cytology cases
• Who was studied: Pathologists at 68 invited institutions, of which 55 responded (45 academic institutions, 7 community hospitals, 2 military institutions, 1 reference laboratory). Separately, 20 patients with histologically confirmed peritoneal or pleural malignant mesothelioma at Northwestern Memorial Hospital, Chicago, 2002 through 2011, who had a fluid cytology specimen within 3 months before histologic confirmation.
• Main results:
  • In the survey table, 36 of 55 respondents (65%) said they make a definitive diagnosis of mesothelioma in cytologic specimens. The results text instead reports 35 (63%).
  • Of 37 respondents answering, 35 (95%) routinely perform immunohistochemistry to support a diagnosis of malignant mesothelioma versus adenocarcinoma.
  • 56% of respondents (18 of 32 in the table) reported using additional ancillary studies (immunohistochemistry or FISH) to establish malignancy in mesothelial proliferations of uncertain malignancy.
  • The feature most often cited as concerning for malignant mesothelioma in an effusion was abnormally large clusters of mesothelial cells: 28 of 34 respondents (82%).
  • Among 13 respondents who do not make a definitive diagnosis, 6 (46%) cited too much overlap with reactive mesothelial cells and 4 (31%) cited inability to assess stromal invasion.
  • Of 51 respondents, 32 (63%) felt clinicians at their institution would treat a patient based on a cytologic diagnosis of malignant mesothelioma. The question covered fine-needle aspirates and effusions together.
  • In the institutional review, 6 of 20 cases (30%) had received a cytologic diagnosis of 'Positive for malignant mesothelioma'. Of the rest, 6 were called atypical, 2 were misclassified as positive for adenocarcinoma, 1 was called suspicious for mesothelioma, and the remainder were classified as benign.
  • There were no false-positive diagnoses of malignant mesothelioma in effusion specimens at the authors' institution during the review period.
• The authors' conclusion: The authors concluded that a majority of respondents will issue a definitive diagnosis of malignant mesothelioma in effusion specimens. They considered this practice supported by published literature documenting excellent specificity of a cytologic diagnosis in the appropriate clinical setting and with supporting ancillary data.
• Limitations the authors state:
  • The authors state that effusion cytology has relatively low sensitivity when morphology alone is considered, and cannot be used to determine the histologic subtype.
  • The survey question on clinician management did not distinguish fine-needle aspiration specimens from effusion specimens.

Topics

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

Medical terms in this study, explained in our Lexicon: Mesothelioma, Cytology, Fluid Cytology, Immunohistochemistry, Adenocarcinoma, Fluorescence In Situ Hybridization (FISH).

Related studies

• Small orangiophilic squamous-like cells: an underrecognized and useful morphological feature for the diagnosis of malignant mesothelioma in pleural effusion cytology — L. Chen, S.G. Caldero, et al. (2014)
• Young investigator challenge: MicroRNA-21/MicroRNA-126 profiling as a novel tool for the diagnosis of malignant mesothelioma in pleural effusion cytology — R. Cappellesso, L. Nicolè, et al. (2016)
• Claudin-4 immunohistochemistry is highly effective in distinguishing adenocarcinoma from malignant mesothelioma in effusion cytology — V.Y. Jo, E.S. Cibas, et al. (2014)
• A diagnosis of malignant pleural mesothelioma can be made by effusion cytology: results of a 20 year audit — A. Segal, G.F. Sterrett, et al. (2013)
• Loss of expression of BAP1 is a useful adjunct, which strongly supports the diagnosis of mesothelioma in effusion cytology — J. Andrici, A. Sheen, et al. (2015)
• 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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