Mohs micrographic surgery for melanoma: A prospective multicenter study.

BACKGROUND: Single-institution studies show that frozen section Mohs micrographic surgery (MMS) is an effective treatment modality for cutaneous melanoma, but no multi-institutional studies have been published. OBJECTIVE: To characterize the use of MMS in the treatment of melanoma at 3 academic and 8 private practices throughout the United States, to recommend excision margins when 100% histologic margin evaluation is not used, and to compare actual costs of tumor removal with MMS vs standard surgical excision. METHODS: Prospective, multicenter, cohort study of 562 melanomas treated with MMS with melanoma antigen recognized by T cells 1 immunostaining. RESULTS: Primary trunk and extremity melanomas (noninvasive and invasive melanoma) achieved histologically negative margins in 97% of tumors with 10-mm margins, whereas 12-mm margins were necessary to achieve histologically negative margins in 97% of head and neck melanomas. Overall average cost per tumor treated was $1328.46. LIMITATIONS: Nonrandomized and noncontrolled study. CONCLUSIONS: MMS with melanoma antigen recognized by T cells 1 immunostaining safely provides tissue conservation and same-day reconstruction of histologically verified tumor-free margins in a convenient, single-day procedure. When comprehensive margin evaluation is not used, initial surgical margins of at least 10 mm for primary trunk/extremity and 12 mm for head/neck melanomas should be used to achieve histologically negative margins 97% of the time.