[Use of immunohistochemistry in clinical cytology]

The purpose of this study was to evaluate the usefulness of immunocytochemical methods of diagnosis in cytology. Pleural effusions and ascites fluids were analyzed from 16 patients in whom the possibility of a malignant effusion was suspected. Cells obtained from the effusions were examined following routine staining by the Papanicolaou method and immunocytochemical staining to determine the presence of tissue specific antigens, i.e. common leucocyte antigen (CLA), cytokeratins (CAM 5.2, AE1), a determinant of the Human Milk Fat Globule (HMFG2) and carcinoembryonic antigen (CEA). The results of the immunocytochemistry studies were compared with the cytologic diagnosis obtained from Papanicolaou stained smears. Good agreement was observed between the diagnosis based on the interpretation of the immunocytochemical studies and the morphological diagnosis. In particular the malignant as well as the benign cells were stained with the epithelial and leucocyte markers according to their tissue origin. Anti-cytokeratin antibody stained epithelial and mesothelial cells, antibody against HFMG2 and anti-CEA stained epithelial (adenocarcinoma) but not mesothelial cells. However macrophages were also positive with anti-CEA antibody. Anti-CLA antibody stained lymphocytes, granulocytes and macrophages but did not distinguish between benign and malignant cells. Based on the results of the present study, immunocytochemical methods using a panel of tissue specific antibodies represent a useful tool in the differential diagnosis of cellular effusions.