The differential diagnosis of epithelial-type mesothelioma from adenocarcinoma and reactive mesothelial proliferation.

Three monoclonal antibodies (mAbs) have been applied to 14 adenocarcinomas, eight mesotheliomas, and nine reactive mesothelial proliferations. One of these, AUA1, is a novel antibody in this context. It was found in 13/14 of the adenocarcinomas but not in benign or malignant mesothelial tissue, making it a potential substitute for carcinoembyronic antigen (CEA) in the differential diagnosis of mesotheliomas from adenocarcinomas. In addition, the lesions were stained using an argyrophil technique to identify nucleolar organizer regions. The results of counting these showed a small but significant overlap in their numbers between malignant and benign mesothelial proliferations. Although there was a difference overall in the numbers of nucleolar organizer regions in adenocarcinomas and mesotheliomas, on the one hand, and benign hyperplasias, on the other, this overlap considerably reduces their value in assessing individual difficult cases.