[Prospective comparison of the diagnostic value of cytology and immunocytology in pleural effusion studied by thoracoscopy and biopsy].

Two issues have been elaborated: the value of immunocytochemistry in the diagnosis of pleural effusions, and the reactivity of the investigated antibodies with different classes of cells in pleural effusions. Effusions of unknown origin from 38 patients were investigated using thoracoscopy, pleural biopsies, conventional cytology, and immunocytochemistry. The following antibodies were used: those monoclonal against various leukocyte antigens, macrophage antigens, epithelial membrane antigen (EMA), various cytoskeleton antigens, and melanoma antigens; those polyclonal against CEA and ferritin. All of the techniques used showed 18 patients (48%) as having a tumor-cell negative effusion. A pleural tumor with a malignant effusion showed in 13 patients (34%); in 12 of these immunocytochemistry also revealed tumor cells. Seven patients (18%) had a tumor of the pleura with a tumor-cell negative effusion; in 2 of these immunocytochemistry revealed a tumor-cell positive effusion. There was no difference with regard to the number of NK cells in patients with inflammation of the pleura and negative cytology and patients with tumor of the pleura and malignant effusion (3% vs 4.5%). Tumor cells were mainly stained by EMA, cytokeratin, and CEA. CEA was the only antibody to be tumor-cell specific, while EMA and cytokeratin were expressed by mesothelial cells also. The antibody against ferritin was a significant marker for mesothelial cells.