Cutaneous Adnexal Carcinomas with Divergent Differentiation

Abstract

Adnexal carcinomas of the skin are rare lesions that encompass multiple histologic patterns. The authors have identified seven neoplasms in this category that showed combined morphologic features of at least two appendegeal tissues. Two manifested pilar and sebaceous differentiation, three showed pilar, sebaceous, and sudoriferous features, and two had sweat glandular and sebaceous characteristics. All tumors arose in the skin of the head and neck; four patients were men and three were women (age range, 21-84 years). One lesion had been present for 25 years with progressive enlargement over the last 3, and another two had slowly expanded over 1-2 years; the duration of growth for the remaining cases was uncertain. Follow-up revealed that six patients were free of disease for at least 1 year after complete excision. In the seventh case, complete excision was performed, but follow-up was not available. Immunohistochemical analysis showed reactivity for keratin and epithelial membrane antigen in each case. Carcinoembryonic antigen was seen in four tumors, and amylase was present in three; none expressed vimentin, S100 protein, or gross cystic disease fluid protein-15. It is concluded that mixed cutaneous adnexal carcinomas are recognizable entities that appear to have little potential for aggressive growth. Immunohistochemical studies may serve as adjuncts to conventional microscopy in the definition of cellular lineages pursued by such neoplasms.