Adenoid cystic carcinoma of the salivary gland and its histologic variants. A clinicopathologic study of thirty cases.

Thirty adenoid cystic carcinomas were seen among 384 salivary gland tumors during the 24-year period from 1952 to 1975. They caused the most difficulty in diagnosis, as they showed a spectrum of histologic appearances. In addition to tumors with the typical cribriform pattern of uniform dark cells, there were some with a more solid basaloid pattern resembling basal-cell carcinomas of the skin. Others manifested both cribriform and basaloid patterns in juxtaposition. A shorter duration of symptoms in lesions with a basaloid component suggests a more rapid growth rate in such tumors. Ultrastructural examination of a tumor with a typical cribriform pattern showed spaces of two types; the more frequent type was bounded by cells with straight plasma membranes and contained filamentous and basement-membrane-like material, and the less frequent type was surrounded by cells with numerous microvilli and contained nonfilamentous homogeneous material. The filamentous and basement-membrane--like material corresponded to connective tissue mucin and the non-filamentous material to epithelial mucin in the light microscopic sections.