Adenocarcinoma is favorably stained for BerEP4 in the membranes [17, 18].In our study, IHC helped identify the site of origin in 21 (77.78%) of the 27 (100%) malignant cases in pleural fluids and 16 (76.19%) of the 21 (100%) cases in peritoneal fluids. This evidence concerns the gene EPCAM and adenocarcinoma.