The role of immunohistochemistry in the diagnosis of neoplastic pleural effusions.

Identification of the origin of neoplastic pleural effusion is a major concern in lung pathology. This study followed the diagnostic role of a panel of antibodies that included calretinin, HBME1, D2-40, Ber-EP4, CK5/6, CEA and TTF1, in a total of 37 cases of pleural and lung cancer with tumor-type cytology, later confirmed by histopathology. For mesothelioma, positive staining for calretinin, D2-40 and CK5/6 and negative for CEA and TTF1 were characteristic. For lung adenocarcinomas, we found Ber-EP4, CEA and TTF1 positivity, and calretinin, D2-40 and CK5/6 negativity. Squamous lung carcinomas were positive for Ber-EP4, CK5/6 and CEA and negative for HBME1, D2-40 and TTF1. The panel of antibodies used in this study provides a differential diagnosis between mesotheliomas and lung carcinomas as well as between lung adenocarcinomas and squamous carcinomas.