EZH2, a unique marker of malignancy in effusion cytology

Our plain-English summary of EZH2, a unique marker of malignancy in effusion cytology, by H. Jiang, R. Gupta, J. Somma (Diagnostic Cytopathology, 2014).

The study

• Authors: H. Jiang, R. Gupta, J. Somma
• Journal: Diagnostic Cytopathology
• Published: 2014;42(2):111-6
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Distinguishing reactive mesothelial cells from metastatic disease, typically adenocarcinoma, in effusion cytology can be challenging at times. We currently use a panel of immunocytochemical markers for select cases including MOC-31 and BerEp4, but difficulties still exist. Enhancer of zeste homologue 2 (EZH2) plays important roles in epigenetic silencing and cell cycle regulation and is upregulated in a wide variety of malignancies. Thus, we hypothesized that EZH2 immunocytochemistry, which to our knowledge has not yet been reported on cytology material, might serve as a unique marker of malignancy in morphologically equivocal effusion specimens by highlighting aberrant protein expression in malignant cells. A total of 96 (48 benign and 48 malignant) effusion cases were selected retrospectively from our department archives. All malignant cases were metastatic adenocarcinomas except for three high grade neuroendocrine carcinomas (two lungs and one ovary), one cervical squamous cell carcinoma, and one epithelioid endometrial stromal sarcoma. The 48 benign cases were all negative for EZH2, and 43 of 48 malignant effusions were positive. As a solitary marker, EZH2 exhibited a sensitivity of 90% and a specificity of 100% (P < 0.0001). EZH2 functioned as a unique and accurate marker of malignancy in this series of effusions. Relative to published data, EZH2 demonstrated a sensitivity comparable to MOC-31 and superior to BerEp4, and a specificity superior to both of these commonly used immunostains. Thus, EZH2 is likely to be of great value as an adjunct to morphology in diagnosing malignancy in effusion specimens.

Copyright © 2013 Wiley Periodicals, Inc.

In plain English

This was a retrospective laboratory study from SUNY Downstate Medical Center in Brooklyn, New York. It tested whether a stain for a protein called EZH2 could help pathologists tell benign (reactive) mesothelial cells from cancer cells in fluid drained from the chest, abdomen or the sac around the heart. The authors stained archived samples from 2010–2011: 48 benign and 48 malignant effusions that were already clear-cut by their appearance under the microscope. The malignant cases were mostly metastatic adenocarcinomas. None were mesotheliomas, and the article does not discuss asbestos. All 48 benign samples were negative for EZH2, and 43 of the 48 malignant samples were positive, a sensitivity of 90% and a specificity of 100%. In a further 36 hard-to-call samples, 14 of 15 judged suspicious for cancer were positive, and all 21 judged to favor reactive cells were negative. The authors concluded that adding EZH2 to a panel of stains is expected to improve accuracy in unclear effusions. They noted that results in everyday practice might differ from this optimized study setting. They also noted that samples were not always received promptly, which may have weakened some 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: Retrospective diagnostic study of archived effusion (body fluid) specimens, testing EZH2 immunostaining against known benign and malignant diagnoses
• Who was studied: 96 morphologically clear-cut effusion cases from 2010–2011 at SUNY Downstate Medical Center, Brooklyn, New York. There were 48 benign effusions (25 pleural, 19 ascitic, 4 pericardial) and 48 malignant effusions (29 pleural, 17 ascitic, 2 pericardial). The malignant cases were all metastatic adenocarcinomas except three high grade neuroendocrine carcinomas, one cervical squamous cell carcinoma and one epithelioid endometrial stromal sarcoma. Mean patient age was 63 (range 15–97), and 68% of the effusions were from female patients. A supplementary group of 36 morphologically equivocal cases was also tested.
• Exposure: No asbestos or other environmental exposure was studied. The test examined was immunocytochemical staining for EZH2 on cell block slides. A case counted as positive when 5% or more of the cells of interest showed nuclear staining.
• Main results:
  • All 48 benign effusions were negative for EZH2, and 43 of 48 malignant effusions were positive.
  • Used as a single marker in the 96 clear-cut cases, EZH2 had a sensitivity of 90% and a specificity of 100% (P < 0.0001).
  • When the non-adenocarcinomas were excluded, 39 of 43 malignant effusions were positive, a sensitivity of 91% (P < 0.0001).
  • Of the five malignant effusions read as negative, the breast cancer case showed no staining. The other four (three lung carcinomas and one pancreatic carcinoma) showed weak or focal staining that was too little to call positive.
  • In 36 morphologically equivocal cases, 14 of 15 cases classed 'suspicious for metastatic carcinoma' were EZH2 positive. All 21 cases classed 'atypical cells, favor reactive mesothelial cells' were EZH2 negative, and 20 of those 21 were negative for MOC-31.
• The authors' conclusion: The authors concluded that using EZH2 in a panel of stains is expected to improve diagnostic accuracy in morphologically equivocal effusions. They added that, with further optimization of the staining protocol, EZH2 might become sensitive enough to serve as a single marker of malignancy. Their comparisons with the stains MOC-31 and BerEp4 relied on figures published by other studies, not on side-by-side testing in this study.
• Limitations the authors state:
  • The authors noted that EZH2 might perform differently in everyday practice than in this optimized study setting.
  • Cases with fewer than 50 cells of interest were excluded, so the authors advised caution for EZH2-negative cases with few suspicious cells.
  • Effusions were received fresh and not always promptly. The authors suggested that delayed or short fixation and alcohol processing may have caused some false-negative stains.
  • The sample included no mesothelioma or melanoma cases and only one sarcoma, so the authors' expectation that EZH2 would help in those cancers was not tested.

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: Cytology, Reactive Mesothelial Cells, Adenocarcinoma, MOC-31, Carcinoma, Squamous Cell Carcinoma, Epithelioid, Sarcoma.

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• 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)
• Evaluation of seven tumour markers in pleural fluid for the diagnosis of malignant effusions — M. Miédougé, P. Rouzaud, et al. (1999)
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