Merkel cell carcinoma. Comparison of Mohs micrographic surgery and wide excision in eighty-six patients.

BACKGROUND: Merkel cell carcinoma is an uncommon malignant tumor of the skin that, after standard surgical excision, tends to recur locally and develop regional nodal spread.

OBJECTIVE: This study evaluated the use of Mohs micrographic surgery for this aggressive neoplasm.

METHODS: A retrospective study of 86 patients with Merkel cell carcinoma established rates of local persistence and the development of regional metastasis after standard surgical excision. Detailed follow-up was available on a subgroup of 13 patients treated with Mohs surgery.

RESULTS: Standard surgical excision for local disease was associated with high rates of local persistence (13 of 41 [31.7%]) and regional metastasis (20 of 41 [48.8%]). Mean follow-up was 60 months. Mean follow-up for the group treated with Mohs was 36 months. Only one of 12 (8.3%) Mohs-treated patients with histologically confirmed clearance has had local persistence of disease. This patient underwent a second Mohs excision and has remained disease free for 84 months. Regional metastasis developed in four of 12 cases (33.3%). Regional metastasis developed in none of the four patients treated with radiotherapy after Mohs surgery and in four of eight patients treated with Mohs surgery without postoperative radiotherapy.

CONCLUSION: Mohs surgery compares favorably with standard surgical excision. Radiotherapy after Mohs surgery may further reduce persistent metastases in transit and nodal disease.