The application of immunocytochemistry to direct smears in the diagnosis of effusions

Our plain-English summary of The application of immunocytochemistry to direct smears in the diagnosis of effusions, by S.M. Knoepp, J. Placido, K.L. Fields, et al (Diagnostic Cytopathology, 2013).

The study

• Authors: S.M. Knoepp, J. Placido, K.L. Fields, D. Thomas, M.H. Roh
• Journal: Diagnostic Cytopathology
• Published: 2013;41(5):425-30
• Cited by: 21 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Metastatic malignancy represents a common cause of effusions. Immunocytochemistry (ICC) is useful in confirming malignancy and gaining insight into the site of origin. Cell blocks are commonly utilized for this purpose; nonetheless, when the malignant cells are sparse, they may not be represented in cell blocks thereby precluding immunophenotypic characterization. Thus, we sought to investigate the utility of direct smear preparations as a platform for ICC in the diagnosis of effusions. Air-dried, unstained direct smears were prepared from 49 malignant effusions and 17 reactive effusions for comparison. ICC for EMA and MOC-31 highlighted the tumor cells in 91 and 98% of the malignant effusions tested, respectively. EMA immunoreactivity was focally observed within the calretinin-positive mesothelial cell population in 1 (6%) of the 17 reactive effusions. ICC for MOC-31 was negative in all reactive effusions. Site-specific immunomarkers were also evaluated. Immunoreactivity for Napsin-A and TTF-1 were observed in 78 and 67% of metastatic lung adenocarcinomas, respectively. ICC for PAX8 highlighted metastatic Müllerian and thyroid carcinomas in 100% of cases tested. CDX-2 immunoreactivity was observed in 25, 60, and 100% of metastatic gastric, pancreatic, and colorectal adenocarcinomas, respectively. Positivity for p63 was observed in 75% of metastatic urothelial cell carcinomas and the one case of pulmonary squamous cell carcinoma examined. Calretinin ICC highlighted the tumor cells in both malignant mesothelioma cases tested as well as the benign mesothelial cells in the reactive effusions. In conclusion, direct smears represent an effective platform for the performance of ICC in the diagnosis of malignant effusions.

Copyright © 2012 Wiley Periodicals, Inc.

In plain English

This laboratory study, from the Department of Pathology at the University of Michigan, tested whether cell stains (immunocytochemistry) could be done on air-dried smears made directly from body-cavity fluid. The usual alternative, cell blocks, can miss scarce cancer cells. The authors examined smears from 49 fluids containing cancer and 17 benign, reactive fluids. Two of the cancers were malignant mesotheliomas. The article does not say where in the body these arose, and it does not discuss asbestos. The stain EMA marked tumor cells in 91% (40/44) of the cancer fluids tested, and MOC-31 marked them in 98% (43/44). In the reactive fluids, MOC-31 was negative in all 17 and EMA was focally positive in 1 of 17. Both mesotheliomas were positive for calretinin and EMA. MOC-31 was negative in one mesothelioma and focally positive (fewer than 10% of tumor cells) in the other. Calretinin also marked the mesothelial cells in all reactive fluids. Among site-specific markers, Napsin-A was positive in 7 of 9 lung adenocarcinomas and TTF-1 in 6 of 9. The authors concluded that direct smears are an effective platform for these stains.

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: Laboratory diagnostic study (case series) applying immunocytochemical stains to direct smears of effusion fluids
• Who was studied: 49 malignant effusions (including 2 malignant mesotheliomas, site not stated) and 17 benign, reactive effusions, studied at the University of Michigan; dates of collection not given
• Exposure: No asbestos or other environmental exposure was studied. What was tested was a laboratory method: immunocytochemistry with eight antibodies (EMA, MOC-31, Napsin-A, TTF-1, p63, PAX8, CDX-2, calretinin) on air-dried, formalin-fixed direct smears
• Main results:
  • EMA stained tumor cells in 91% (40/44) of the malignant effusions tested
  • MOC-31 stained tumor cells in 98% (43/44) of the malignant effusions tested
  • In the reactive effusions, focal EMA positivity (under 10%) was seen in the mesothelial cells in 6% (1/17). Calretinin was positive in the mesothelial cells in all cases
  • Both malignant mesothelioma cases (2/2) were positive for calretinin
  • MOC-31 was focally positive (under 10% of tumor cells) in one malignant mesothelioma case and negative in the other
  • In metastatic lung adenocarcinoma, Napsin-A was positive in 78% (7/9) of cases and TTF-1 in 67% (6/9)
• The authors' conclusion: The authors concluded that direct smears of effusions are a robust source of cellular material and an effective platform for immunocytochemistry.

Topics

Medical terms in this study, explained in our Lexicon: Cell Block, MOC-31, Calretinin, Mesothelial Cells, Thyroid Transcription Factor-1 (TTF-1), Lung Adenocarcinoma, Carcinoma, Adenocarcinoma.

Related studies

• Cytological differential diagnosis among adenocarcinoma, epithelial mesothelioma, and reactive mesothelial cells in serous effusions by immunocytochemistry — X.Y. Su, G.D. Li, et al. (2011)
• Immunocytochemistry and ELISA quantitation of mucin for diagnosis of malignant pleural effusions — P.C. Yang, K.T. Luh, et al. (1992)
• A panel of markers for identification of malignant and non-malignant cells in culture from effusions — F.P. Carneiro, M.I. Muniz-Junqueira, et al. (2017)
• Claudin-4 immunohistochemistry is highly effective in distinguishing adenocarcinoma from malignant mesothelioma in effusion cytology — V.Y. Jo, E.S. Cibas, et al. (2014)
• The diagnostic utility of D2-40, calretinin, CK5/6, desmin and MOC-31 in the differentiation of mesothelioma from adenocarcinoma in pleural effusion cytology — T.S. Hyun, M. Barnes, et al. (2012)
• 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)

Browse more research in Diagnostic Cytopathology, or return to medical research.