Microcystic adnexal carcinoma: review of a potential diagnostic pitfall and management.

Microcystic adnexal carcinoma (MAC) is an uncommon, locally aggressive cutaneous neoplasm that usually presents as a slow-growing, asymptomatic lesion on the head or neck. Microcystic adnexal carcinoma frequently is misdiagnosed due to its histologic appearance on superficial biopsy specimens mimicking other follicular neoplasms. Herein, we highlight a case in which a slow-growing lesion was initially diagnosed as a trichoadenoma following superficial biopsy; however, after surgical excision the pathology revealed a locally aggressive MAC.