Microcystic adnexal carcinoma (MAC) is an infiltrative cutaneous tumor that most often presents as a scar-like papule or plaque on sun-exposed skin. Historical terms that have been used to refer to this tumor include sclerosing sweat duct carcinoma, malignant syringoma, and syringoid carcinoma. Tissue invasion by MAC frequently extends far beyond the clinical margins of the tumor. In addition, perineural involvement is common.
Although metastasis and death from MAC are rare events, significant morbidity can occur as a result of deep local tissue invasion, and treatment of MAC is recommended. Surgery that results in complete removal of the tumor is the treatment of choice for MAC.
The epidemiology, diagnosis, and management of MAC will be discussed here.
MAC is a rare tumor that was first described in 1982 . In retrospect, earlier reports documented this tumor prior to its recognition as a distinct entity .
The vast majority of reported cases of MAC have been in white individuals; however, MAC can also occur in other populations [3-8]. An analysis of data from the Surveillance, Epidemiology, and End Results (SEER) database collected between 1973 and 2004 found an incidence rate of 6.5 per 10 million white individuals . The incidence rates for black subjects and Asian/Pacific Islanders were significantly lower at 1.9 and 1.6 per 10 million individuals, respectively .