Microcystic adnexal carcinoma (MAC) affects predominantly the face and seldom metastasizes. We report a case occurring in the axilla of a 63-year-old male. Histology revealed the characteristic features of MAC. Eleven months after the excision, he underwent a reexcision with wide margins because of local recurrence. Histologically, the central area of the recurrent lesion revealed the typical histologic features of MAC, and the periphery showed a proliferation of irregular duct-like and glandular structures with a mixed pattern. Two lymph nodes that were not adherent to the tumor had metastatic tumor cells. The present case confirms that MAC can metastasize, although it may also be hypothesized that the recurrent lesion represented transformation into a higher-grade carcinoma.

Will MAC be back?ANZ J Surg. 2003 Oct;73(10):830-2.

BACKGROUND: Microcystic adnexal carcinoma (MAC) was first described as a specific entity in 1982 by Goldstein et al. MAC is a very aggressive tumour, displaying locally invasive tendencies with perineural invasion. For this reason previous studies have suggested that Mohs micrographic surgery is a superior technique in establishing clear margins of excision. However, there is no evidence to suggest that standard local excision is less effective in achieving tumour clearance or a more favourable outcome. METHODS: All patients with MAC were identified from the pathology database. All patients who had undergone local excision were reviewed and included in the study. Histopathology was reviewed by dermatopathologists. RESULTS: We reviewed the outcome of 17 patients treated with local excision. Eleven were female and six were male with a mean age of 70 years, and a mean follow up of 30 months. Two patients in this series experienced recurrence after standard local excision. The mean lateral and depth margins were 7.69 mm (range 0.2-21) and 4.66 mm (range 1-14.5), respectively. Recurrence occurred in two out of three patients who had lateral clearance margins of less than 4 mm. These two patients had evidence of perineural invasion on histopathology. CONCLUSION: In the present study, standard local excision is shown to be effective in tumour clearance for MAC with no recurrences provided there are lateral margins of at least 4 mm. However, a longer period of follow up is required because of the very aggressive locally invasive nature of the tumour.

Clinical course, risk factors, and treatment of microcystic adnexal carcinoma: a short series report.Dermatol Surg. 2003 Oct;29(10):1035-8.

BACKGROUND: Microcystic adnexal carcinoma (MAC) is a locally aggressive neoplasm of both eccrine and follicular differentiation; it commonly presents on the head and neck of white middle-aged to older patients. OBJECTIVE: To review the course, risk factors, and management of 10 patients with microcystic adnexal carcinoma (MAC) and to compare treatment outcome by either Mohs micrographic surgery or standard surgical excision. METHODS: Tumor registry databases were used to identify cases at Roswell Park Cancer Institute in Buffalo, New York. Fifteen cases that were coded as MAC were reviewed. Ten cases were subsequently confirmed to be MAC. From these cases, data were collected on patient demographics, tumor location and size, risk exposure, metastasis, treatment, and recurrence of tumors. RESULTS: The average age of the patients was 63.4, and females outnumbered males seven to three. Nine tumors were located on the head and neck area. Five patients had a history of radiation therapy, and two patients were sisters. The first-time procedure was Mohs micrographic surgery in four cases and surgical excision in six cases. Three patients in the surgical excision group needed a second procedure, two of whom thereafter underwent Mohs micrographic surgery. In the Mohs micrographic surgery group, none of the patients required a second procedure, and all of the patients were disease free at an average of 23.3 months. One recurrence was noted in the surgical excision group, and the average follow-up was 32 months. CONCLUSION: This report supports the use of Mohs micrographic surgery for tumor control with the least possible procedures. Risk factors appear to include radiation treatment, ultraviolet exposure, and possibly genetics.