beta-2-Microglobulin in primordial and differentiated basocellular carcinomas and basosquamous carcinomas

27 cases of basocellular carcinomas and basosquamous carcinomas of the skin were classified into primordial and differentiated basocellular carcinomas and basosquamous carcinomas and stained for beta-2-microglobulin using the immunoperoxidase technique. All the differentiated basocellular carcinomas and some of the basosquamous carcinomas contained beta-2-microglobulin, but none was found in the primordial basocellular carcinomas. Staining of basal cell tumors for beta-2-microglobulin may be helpful in interpreting adnexoid and epidermoid differentiation in skin tumors.