Mohs micrographic surgery is accurate 95.1% of the time for melanoma in situ: a prospective study of 167 cases.

BACKGROUND

Mohs micrographic surgery (MMS) represents a promising option for treatment of melanoma in situ (MIS). However, interpretation of melanocytic lesions by fresh frozen sections may be difficult.

OBJECTIVE

The objective of this study was to determine if margins called clear by MMS were clear by subsequent paraffin-embedded sections and to compare cure rate with available data for MMS and standard excision.

MATERIALS AND METHODS

A total of 167 patients with MIS, including 116 patients with MIS in sun-exposed skin of lentigo maligna (LM) type, were treated by MMS with subsequent evaluation of the final margin with paraffin-embedded sections that were cut en face, over a period of 12 years. A total of 143 patients were available for follow-up from 6 months to 12 years (mean, 50 months; median 48 months; 594.5 patient-years), and 109 patients were available for follow-up from 2 to 12 years (mean, 63 months; median, 60 months; 569 patient-years).

RESULTS

The clearance rate by MMS technique using frozen sections was 94.1% for MIS non-LM type, 95.7% for MIS LM type, and 95.1% for both. The cure rate was 97.8% for MIS non-LM type, 99.0% for MIS LM type, and 98.6% for both for mean follow-up of 50 months and 97.4% for MIS non-LM type, 98.6% for MIS LM type, and 98.2% for both for mean follow-up of 63 months.

CONCLUSION

MMS is a viable option for treatment of MIS that may increase cure rate and reduce the size of the defect especially in cosmetically and functionally sensitive areas.