Sweat gland differentiation in mammary adenoid cystic carcinoma

A breast tumor is described which presented as an exophytic mass, and which by both light and electron microscopic examination had a biphasic histologic composition. In the superficial area adjacent to the epidermis, it showed tubular differentiation similar to a cutaneous tubular apocrine adenoma and salivary basal cell adenoma, and, in the deeper portion, it had the characteristic features of adenoid cystic carcinoma. Their possible interrelationships are discussed, and mammary adenoid cystic carcinoma is briefly reviewed.