MOHS MICROGRAPHIC SURGERY LOCAL RECURRENCES

BACKGROUND. Even though 5-year cure rates are as high as 99% for Mohs micrographic surgery (MMS) of cutaneous carcinomas, theoretically 100% cure rates of unifocal carcinomas should be possible. OBJECTIVE. To determine why cutaneous malignancies recur locally (persist) after MMS. METHODS. A retrospective study of all cutaneous malignancies treated with MMS during a 4-year period at Washington University School of Medicine was made. All lesions that were locally recurrent after previous MMS were analyzed for any possible cause of the recurrence. RESULTS. Of 2,414 cutaneous malignancies treated, 33 (1.4%) were locally recurrent after previous MMS by four different Mohs surgeons and five separate technicians. Technical or interpretation problems that could have accounted for the local recurrence were identified in 77% of the lesions. The mean time to recurrence was 38.5 months, with 20% developing more than 5 years after the initial MMS. CONCLUSION. MMS local recurrences are rare with procedural errors representing a majority of them. Five-year cure rates for basal cell carcinoma may somewhat overestimate the ultimate cure rate.