Cytological differential diagnosis among adenocarcinoma, epithelial mesothelioma, and reactive mesothelial cells in serous effusions by immunocytochemistry.

The objective of the study is to estimate the expression of some antibodies in the metastatic adenocarcinomas, malignant epithelial mesotheliomas, and reactive mesothelial cells in serous effusions and to choose effective panel to the differential diagnosis. Totally 113 effusion cytology samples (80 pleural fluid, 30 ascitic, and 3 pericardial fluid) from 60 cases of metastatic adenocarcinoma (ACA), 18 cases of malignant epithelial mesothelioma (MM), and 35 cases of reactive mesothelium (RM) were included in this study. The cytological diagnoses of these cases were confirmed by histopathology or clinical datas. Smears and cell blocks were prepared for each case. Immunocytochemical study was performed on the cell block sections. The sensitivity of E-cadherin, CEA, MOC-31, and Ber-EP4 for adenocarcinoma was 86.7%, 80%, 70%, and 76.4%, respectively. The specificity was 98.1%, 96.2%, 92.5%, and 86.8%, respectively. The sensitivity of calretinin, HBME-1, and thrombomodulin for RM/MM was 83%, 79.2%, and 47.2% respectively. The specificity was 88.3%, 21.7%, and 70%, respectively. The expression of E-cadherin, CEA, MOC-31, Ber-EP4, calretinin, and thrombomodulin showed significant difference between ACA and RM/MM (P < 0.01). The reactivity of EMA and Des showed significant difference between RM and MM (P < 0.01). In our opinion, the antibody panel that consists of E-cadherin, CEA, calretinin, and thrombomodulin should be the best for differential diagnosis between metastatic adenocarcinomas and RM/MM in serous effusions. EMA and Des should be used to differentiate malignant epithelial mesothelioma and reactive mesothelial cells. EMA positive and Des negative favor MM, while Des positive and EMA negative favor RM.