Immunohistochemical study of lysozyme, alpha 1-anti-chymotrypsin, tissue polypeptide antigen, keratin and carcinoembryonic antigen in effusion sediments.

The cellular sediments of 42 malignant and 16 benign effusions (58 cases) were studied using the immunoperoxidase technique. Serial sections of formalin-fixed, paraffin-embedded residual sediments of effusions, sent for routine cytologic examination, were studied by commercially available polyclonal antisera against lysozyme, alpha 1-anti-trypsin, alpha 1-anti-chymotrypsin, tissue polypeptide antigen (TPA), a wide-spectrum anti-keratin, carcinoembryonic antigen (CEA) and, in single cases, thyroglobulin and prostate-specific antigen. A final definite diagnosis from histologic study of biopsy or autopsy specimens was known in all cases. All carcinomas, the mesotheliomas and the reactive mesothelial cells showed a positive reaction for TPA and, partly, the wide-spectrum keratin. Lysozyme could be demonstrated in the cells of the one proven malignant fibrous histiocytoma; all malignant epithelial cells were negative. Alpha 1-anti-chymotrypsin and alpha 1-anti-trypsin showed similar reactions: they were often positive in carcinoma cells of the breast, the bronchial system and the pancreas, in contrast to a mostly negative reaction in carcinomas of the stomach and ovary. CEA showed considerable differences; it was always negative in benign and malignant mesothelial proliferations but mostly positive in carcinomas of the stomach, pancreas and bronchial system. It was only positive in less than 20% of the carcinomas of the breast and always negative in the proven malignant effusions of primary carcinomas of the ovary and prostate. Studying a combination of several tumor markers is possible in serial paraffin-embedded sections and may be a valuable criterion in the cytologic diagnosis of effusions.