A review of adenoid cystic carcinoma of the breast with emphasis on its molecular and genetic characteristics.

Breast carcinomas that do not express estrogen receptor α, progesterone receptor, or human epidermal growth factor receptor 2 are frequently grouped together as "triple negative" and considered an aggressive type of breast malignancy; however, this group is not homogeneous. Adenoid cystic carcinoma of the breast is a rare type of breast cancer with such triple-negative features and, generally, a more favorable clinical course. This comprehensive review describes diagnostic, molecular, and clinical features of adenoid cystic carcinoma and compares them with those of triple-negative breast carcinomas of no special type.