Mohs micrographic surgery

Published Date: 19th July 2016

Publication Authors: Tehrani H

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Microcystic adnexal carcinoma (MAC) is a locally aggressive tumour with a propensity for perineural and perivascular invasion, resulting in a high recurrence rate even with wide surgical margins (Leibovitch I, Huilgol SC, Selva D et al. Microcystic adnexal carcinoma: treatment with Mohs micrographic surgery. J Am Acad Dermatol 2005; 52: 295-300). We present two patients who had Mohs micrographic surgery (MMS) in order to excise MACs. An 84-year-old man presented with a lesion on the right lower eyelid that had been neglected for a number of years. Initial biopsy indicated morphoeic BCC, and a magnetic resonance imaging scan showed abnormal soft tissue within the right lower eyelid extending to the conjunctiva. Due to orbital involvement an exenteration was carried out; histology was reported as MAC incompletely excised at the medial peripheral margin. The patient was referred for MMS to the involved area, subsequently undergoing two excision stages and repair with a split-thickness skin graft. At the 1- year follow-up there was no evidence of recurrence. A 59- year-old woman had a lesion excised from the right eyebrow, which was reported as a possible syringoma. The lesion recurred after 5 years and further excision revealed an incompletely excised MAC. The patient was referred for MMS, and after a detailed history was taken it was noted that the patient had symptoms consistent with perineural invasion. On examination there was a firm subcutaneous lesion present at the scar site. The lesion proved to be extensive, displaying both perineural and perivascular invasion, and required 10 Mohs excision stages to gain tumour clearance. The defect was repaired with a forehead flap and the patient made an uneventful recovery with no recurrence 6 months postoperatively. She retained function in her right eye, which would have undergone exenteration if MMS were unavailable. MMS has been shown, in small series, to provide a lower recurrence rate than formal excision and has been proposed as the mainstay of treatment for MAC. Recurrence rates after MMS have been reported as low as 0-12% (Snow S, Madjar DD, Hardy S et al. Microcystic adnexal carcinoma: report of 13 cases and review of the literature. Dermatol Surg 2001; 27: 401-8). Our cases serve to highlight the role of MMS in the treatment of MAC, and we agree with other authors who suggest that MMS should be employed either as a primary treatment modality, or as an adjunct for cases having undergone incomplete excision.

Jayasekera, P; Sharpe, G; Tehrani, H. (2014).  The role of Mohs micrographic surgery in the treatment of microcystic adnexal carcinoma . British Journal of Dermatology. 171 (Supplement S4), 75

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