Diagnostic utility of BRCA1-associated protein 1 (BAP1), Programmed Cell Death4 (PCD4) and Epithelial membrane antigen (EMA) expression in differentiation of malignant mesothelioma from reactive mesothelial cell hyperplasia in both cytology and cell block

Abstract

Background: Malignant pleural mesothelioma (MPM) is the most lethal tumor arising from the mesothelial cells. Sometimes, it is difficult to be diagnosed based on morphology alone as reactive mesothelial hyperplasia (RMH) and some metastatic carcinomas may be confused with mesothelioma. Aim of the study: Our study aims to evaluate diagnostic utility of BRCA1 “Breast Cancer gene” associated protein-1 (BAP1), Programmed Cell Death (PCD4), and Epithelial membrane antigen (EMA) in differentiation of malignant mesothelioma (MM) from reactive mesothelial hyperplasia (RMH) by immunohistochemistry (IHC).Material and methods: Retrospective study, include 60 patients, was carried out in Chest and Pathology Departments of Zagazig University from October 2016 till August 2020. The expression levels of BAP1, PCD4and EMA were investigated using cytological analysis compared with cell block method in all cases of MPMs and RMHResults: BAP1loss was detects malignant mesothelioma confirmed by cytology in 19 out of 20 patients with sensitivity of 95%, specificity 92.5%, PCD4 was positive in 39 out of 40 patients of RMH and can diagnose reactive mesothelioma with a sensitivity of sensitivity of 85.7%, specificity 100%. EMA was positive 95% in MM confirmed by cytology and can diagnose malignant mesothelioma with a sensitivity of 95%, specificity 97.5%. Conclusion: Increased sensitivity of diagnosis by cell block method was observed in cases that were reported as reactive mesothelial hyperplasia by conventional smears. BAP1 loss, negative PCD4 immunostaining and positive EMA favor mesothelioma.Keywords: BAP1, PCD4, EMA, malignant mesothelioma.