Extramammary Paget's disease (EMPD) is an uncommon tumor that has a high rate of recurrence after conventional surgical treatments.

Our purpose was to establish the efficacy of Mohs micrographic surgery (MMS) in the treatment of EMPD, and to make treatment recommendations with regard to surgical margins. We also attempted to summarize the published recurrence rates of EMPD after standard surgical management.

In a retrospective chart review, pertinent demographic data, tumor data, treatment characteristics, and follow-up data were tabulated. A search of the literature for recurrence rates after MMS and non-MMS surgical treatment modalities was performed.

The recurrence rate after treatment with MMS was 16% for primary EMPD and 50% for recurrent EMPD. The 5-year tumor-free rates (Kaplan-Meier analysis) were 80% for primary tumors and 56% for recurrent tumors. Using MMS, the salvage rate (and, hence, overall cure rate) was 100%. Margins of 5 cm were required to clear 97% of the tumors. The recurrence rate after non-MMS (from the literature) is 33% to 60%.

MMS is effective, and superior to standard surgical management in the treatment of EMPD. We recommend a 5-cm margin of normal skin if MMS cannot be offered.