Adenoid cystic carcinoma of the breast. Light and electron microscopy and a brief review of the literature.

The case of two patients with adenoid cystic carcinoma of the breast are reported. In case 1, the predominant pattern was that of a solid, basaloid, cylindromatous tumor, whereas case 2 showed the typical adenoid cystic appearance. Results of electron microscopical study confirmed that many of the cystic spaces seen by light microscopy were extracellular compartments enclosed by tumor cells. Many of the tumor cells contained densely packed fibrils, which support the myoepithelial origin of these tumors. Approximately 92 well-documented reports of this lesion are briefly reviewed.