SM047 immunoreactivity in peritoneal fluids

Abstract

SM047 is a recently developed monoclonal antibody generated against an ovarian adenocarcinoma cell line. A recent immunohistochemical study has shown that SM047 is strongly expressed in tissue sections of most ovarian serous adenocarcinomas. This study aimed to ascertain whether SM047 staining is of value in cytological preparations of peritoneal fluid. A total of 206 consecutive peritoneal fluids were stained immunocytochemically with SM047, CA125, monoclonal carcinoembryonic antigen (mCEA), Ber-EP4 and cytokeratins (CK7 and 20). SM047 positivity was present in reactive mesothelial cells in 117 of 141 (83%) benign cases in which these were present. SM047 positive tumour cells were present in 22 of 23 (96%) ovarian serous adenocarcinomas and in small numbers of gastric adenocarcinomas (two of three), mesotheliomas (one of two) and pancreatic adenocarcinomas (one of one). All six colorectal and two breast adenocarcinomas were negative with SM047. Reactive mesothelial cells in all cases were positive with CK7 and in most cases with CA125. They were negative with CEA, Ber-EP4 and CK20. All adenocarcinomas were positive with Ber-EP4 and mesothelial cells were always negative. All colorectal adenocarcinomas were positive with CK20. This study shows that SM047 staining may be of value in the diagnosis of an ovarian serous adenocarcinoma in peritoneal fluids. Negative staining helps to exclude a primary ovarian serous adenocarcinoma and is characteristic of colorectal adenocarcinoma. The small numbers of other malignancies in the study precludes a judgement of the value of SM047 staining in these neoplasms. SM047 staining may be useful, as part of a larger panel, in the work up of patients with peritoneal effusions.