HBME-1 a monoclonal antibody useful in the differential diagnosis of mesothelioma, adenocarcinoma, and soft-tissue and bone tumors

HBME-1 monoclonal antibody has recently become available as a suggested immunohistochemical tool for the positive identification of malignant mesothelioma. In this study, the HBME-1 antibody was immunohistochemically evaluated on selected normal tissues and in 540 epithelial and nonepithelial tumors of different organs. Most mesotheliomas (25 of 29) showed a strong reactivity, with either a luminal or a cytoplasmic pattern. However, less differentiated mesotheliomas with sarcomatous features as well as sarcomatous areas of otherwise more differentiated mesotheliomas were negative. With regard to carcinomas, about half of the adenocarcinomas of the lung showed reactivity that was usually less conspicuous than the reactivity observed in mesothelioma. Consistently positive adenocarcinomas included endometrial and ovarian serous carcinomas. Thyroid lesions reacted differently: papillary and follicular carcinomas were strongly positive, whereas follicular adenomas and normal tissues were usually negative, suggesting that HBME-1 may be helpful in the evaluation of thyroid lesions. While gastric and pancreatic adenocarcinomas showed positivity in a minority of cases, tumors from the breast only rarely showed significant reactivity. Adenocarcinomas of colon, kidney, and prostate were almost invariably negative. Among soft-tissue and bone tumors, chordoma and cartilaginous tumors were strongly positive, and synovial sarcoma showed reactivity in the epithelial component. Other sarcomas and melanomas were negative. On the basis of our findings, HBME-1 monoclonal antibody is helpful in the differential diagnosis of mesothelioma, but because adenocarcinomas of many sites, including lung, are sometimes strongly positive, this antibody has to be used in a panel with other antibodies. We believe that the HBME-1 antibody could replace one of the antibodies that is typically negative in mesothelioma and positive in carcinoma. Interestingly, HBME-1 appears to be useful in subtyping lesions of certain organs, primarily thyroid tumors, soft-tissue and bone tumors of cartilaginous differentiation, and those with epithelial traits.