Background: Malignant mesothelioma (MM) is an aggressive tumor that arises from the mesothelial cells that form the lining of the pleural, pericardial, and peritoneal cavities. Distigushing between bengin and malignant mesothelial proliferation on effusions is a challenge. BRCA1-associated protein 1 (BAP-1) was proposed to aid in distinguishing malignant mesothelioma (MM) from mesothelial hyperplasia( MH ).
Aim of the work: This study aims to evaluate the diagnostic utility of BRCA-1 associated protein-1( BAP-1) immunohistochemistry in distingushing between reactive and neoplastic mesothelial cells in both pleural biopsy and pleural effusion and correlate the results of clinico-pathological finding.
Material and methods: This is a retrospective study on 61 cases of pleural biopsy and pleural cell block. Thity six (36) cases of pleural biopsy were diagnosed as malignant mesothelioma, out of 25 cell blocks, fifteen (15) cases were reactive mesothelial proliferation and ten (10) cases were atypical mesothelial proliferation, stained with BAP-1.
Results:
BAP-1 expression in mesothelioma considered as; positive staining when > 67.5% of target cells show immunoreactivity, negative staining when < 67.5% showed immunraectivity. BAP-1 expression in cytology considered as; positive staining when > 57.5% of target cells show immunreactivity, negative staining when < 57.5% showed immunraectivity.. BAP1expression significantly lost in atypical mesothelial proliferation which were proved later to be mesothelioma and mesothelioma cases (P value