Histologic and ultrastructural features of adenoid cystic carcinoma of the breast.

Abstract

Five examples of adenoid cystic carcinoma of the breast were examined histologically, and an electron microscopic study was carried out in one of them. In 2 tumors, areas histologically indistinguishable from benign mixed tumors of salivary gland origin were observed. Ultrastructural studies disclosed that the cysts which give the tumor its name are extracellular compartments lined by a basement membrane and filled with material apparently derived from the lamina densa. Infrequent true ducts and intercellular spaces containing cilia were observed. There was no evidence of secretory activity in tumor cells. It was concluded that adenoid cystic carcinoma of the breast is most likely of duct origin. Comparable studies of salivary gland tumors and of the role of the myoepithelial cells in the formation of adenoid cystic carcinoma were discussed.