Distinction between cells in serous effusions using a panel of antibodies

In serous effusions the distinction between reactive mesothelial cells and malignant cells (especially adenocarcinoma cells and malignant mesothelial cells) is frequently a cause of diagnostic difficulty. The present paper describes the immunocytochemical staining of cells in 76 effusions from 71 patients with different malignancies. In 91% of the effusions obtained from patients with adenocarcinomas, the cells stained positive for anti-EMA, 94% for anti-CEA, 64% for anti-LeuM1-antigen and 75% for anti-keratins. In more than 90% of the cases the reactive mesothelial cells stained positive for anti-keratins, but not for anti-EMA, anti-CEA or anti-LeuM1-antigen. It is concluded that a panel of the antibodies against EMA, CEA, LeuM1-antigen and keratins is valuable in the distinction between adenocarcinoma cells, malignant mesothelial cells and reactive mesothelial cells in serous effusions.