Microcystic Adnexal Carcinoma: A Rare, Commonly Misdiagnosed Malignancy.

Microcystic adnexal carcinoma (MAC) is a rare, malignant cutaneous neoplasm that often presents as an inconspicuous, benign appearing lesion. Patients most commonly are asymptomatic and present for improved cosmesis, however perineural invasion may result in local numbness, paresthesia or pruritus. Although distant metastasis is rare, MAC has an increased propensity for local invasion, often resulting in significant morbidity as late presentation and misdiagnosis are common.