The diagnostic value of loss of BAP1 (BRCA1 associated protein) and MTAP (methylthyoadenosinephosphorylase) in pleural effusion cytologies in mesothelial proliferations

Pleural mesothelioma (PM) is an aggressive neoplasm associated with asbestos. Differentiation from reactive mesothelial hyperplasia (RMH) creates difficulties in diagnosis. EMA and desmin immunohistochemical (IHC) markers are used as an aid in this distinction. Diagnosis of mesothelioma in cytological specimens is a controversial issue. In this thesis, the utility of BAP1, MTAP, EMA, desmin IHC markers in the differential diagnosis of cytological specimens was analyzed. 49 PM and 43 RMD cases were included in the study group. It was observed that 61.2% of the PM group had a loss with the BAP1 IHC determinant. No loss was observed in the RMH group. With the MTAP IHC determinant, loss was observed in 44.9% of the PM group and 11.6% of the RMH group. The EMA IHC marker showed immunoexpression in 73.5% of the PM group and 4.7% of the RMH group. No immunoexpression was detected in the PM group with the Desmin IHC marker. In the RMH group, immunoexpression was detected at a rate of 67.4%. The BAP1 IHC marker has the highest specificity and the desmin marker has the highest sensitivity. As a result, all determinants were found to be statistically significant in discrimination. Key Words: Mesothelioma, Pleural Effusion Supporting Institutions: Eskişehir Osmangazi University Scientific Research Projects Commission