Adenosquamous carcinoma of the skin: a report of 10 cases.

Cutaneous squamous carcinoma with true glandular differentiation has only rarely been documented. Ten patients with such tumors are presented. There were six men and four women, aged 48 to 87 years. The tumors were located on the central face (eight), scalp (one), and hand (one) and consisted of minimally elevated, indurated, keratotic plaques, up to 6 cm in size. Microscopically, the neoplasms exhibited multifocal origin from the epidermis; deep, dispersed, infiltrative growth; perineural invasion; and stromal desmoplasia. Squamous differentiation was most marked superficially. Glandular differentiation was more obvious in deeper areas. Lumens typically developed within squamous nests and were often lined by cells with cytoplasmic vacuoles, some of which contained mucin. The neoplastic cells had obvious cytologic atypia and easily identified mitotic figures. Immunohistochemically, nine neoplasms studied contained carcinoembryonic antigen in glandular foci. Each patient had one or more surgical resections, and six also received radiation and/or chemotherapy. Five patients died with uncontrolled local recurrence, and two are alive with extensive disease and clinical evidence of regional lymph node involvement. Two individuals with small, superficial neoplasms that could be completely removed are disease free. One patient died of unrelated causes shortly after diagnosis. Cutaneous adenosquamous carcinoma is more aggressive than the usual carcinoma of the skin. It must be distinguished from the cytologically bland, microcystic adnexal (sclerosing sweat duct) carcinoma which is capable of recurring but rarely, if ever, proves fatal. The question of whether adenosquamous carcinoma is an epidermally derived squamous tumor with divergent differentiation or should be viewed as a newly recognized adnexal carcinoma remains to be resolved.