Immunohistological study of malignant diffuse mesotheliomas of the pleura.

Paraffin sections from fifteen cases of malignant diffuse mesothelioma of the pleura and five cases of bronchial adenocarcinoma infiltrating the pleura were examined with an antiserum specific for factor VIII related antigen and with antisera against various epithelial markers: keratin, carcinoembryonic antigen (CEA), fat globule membrane antigen and secretory component. In all adenocarcinomas all the epithelial markers were present whereas the factor VIII related antigen was absent. The distribution of the fat globule membrane antigens, keratin, secretory component and factor VIII related antigen varied from one mesothelioma to another. The mesotheliomas were generally negative for CEA. The three mesotheliomas which were positive for CEA were also positive for alcian blue after hyaluronidase treatment. Amongst the markers used, CEA seems the most useful for the differential diagnosis between carcinoma and mesothelioma. However, the simultaneous detection of several markers allows the characterization of various phenotypes. Some of them are close to the phenotypes of true adenocarcinoma. A relation between a given phenotype and the biological behaviour of the tumour has still to be demonstrated.