CD31 IMMUNOREACTIVITY IN CARCINOMAS AND MESOTHELIOMAS

CD31 is a specific and sensitive marker of endothelial differentiation . Previous reports have described its immunoreactivity in large series of soft tissue neoplasms, as well as its comparison with other availa ble and commonly used endothelial markers. CD31 reactivity in carcinom as or mesotheliomas has been incompletely addressed, however Hence, we applied anti-CD31 (JC70/A, DAKO, Carpinteria, Calif) to 290 previousl y characterized neoplasms by using a modified avidin-biotin-peroxidase complex technique following microwave epitope retrieval. Seven carcin omas showed plasmalemmal-based immunoreactivity (2 papillary thyroid c arcinomas, 2 mucoepidermoid salivary gland carcinomas, 1 cutaneous adn exal tumor, 1 cutaneous squamous cell carcinoma, and 1 esophageal squa mous cell carcinoma); the remaining 283 lesions were negative for this marker We conclude that anti-CD31 immunostaining in carcinomas and me sotheliomas is rare. These findings support the concept that CD31 is a reliable marker of endothelial differentiation and should be included in diagnostic immunohistochemical panels when vascular tumors enter t he differential diagnosis.