Abstract

Cytologic diagnosis of reactive or malignant effusion is sometimes difficult. Espe- cially, differentiation of benign reactive mesothelial cells from malignant cells in body effusion is more difficult. Recently, immunohistochemistry has been used to diagnose difficult cases. Phospholipase C(PLC)-gamma 1 is one of the isoenzyme of the PLC which plays central role in signal transduction involving cellular growth, differentiation and transformation by phosphorylating many protein component. Increased expression of PLC-gamma 1 in human breast carcinoma, colorectal carcinoma and stomach cancers are reported. To evaluate the efficacy of positive PLC-gamma 1 immunostaining in the diagnosis of malignancy in effusions, paraffin-embedded cell blocks of pleural fluid and ascites from 10 patients(5 metastatic adenocarcinomas, and 5 reactive mesothelial cells) were immunostained with a monoclonal antibody to PLC-gamma 1. PLC-gamma 1 immuostained all the adenocarcinomas in cell block(5/5) with intense membrane pattern, however, none of the reactive mesothelial proliferations stained with the diagnostic membrane pattern. Thus, our study strongly supports the conclusion that PLC-gamma 1 immunopositivity is likely to become a useful adjunct for the diagnosis of malignancy in effusions.

• Keywords: PLC-1;immunohistochemical stain;body effusion