Tissue-sparing properties of Mohs micrographic surgery for infiltrative basal cell carcinoma.

BACKGROUND: Mohs micrographic surgery (MMS) should lead to tissue sparing of healthy skin compared with standard surgical excision because smaller surgical margins are used.

OBJECTIVE: To quantify the tissue-sparing properties of MMS in primary basal cell carcinoma (BCC) with an infiltrative growth pattern.

METHODS: A prospective study including 256 primary BCCs with an infiltrative growth pattern was performed. Tumor sizes were measured in 2 perpendicular directions. Surface defect areas after MMS were measured. The suspected defect surface area with standard excision using a 5-mm margin was calculated. The primary outcome of this study was the size of the defect surface area spared with MMS compared with the calculated defect surface area with a standard excision.

RESULTS: The median tumor size was 71 mm2 , and the median defect size after MMS was 154 mm2 . The median defect size calculated for standard surgical excision was 298 mm2 . We have shown that MMS of BCC with an infiltrative growth pattern had a 46.4% tissue-sparing effect when compared with standard surgical excision (95% confidence interval, 43.4%-49.1%; P value < .001).

LIMITATIONS: Single-center study design. Lack of a randomized control group for ethical reasons.

CONCLUSION: A rate of tissue sparing of 46% can be reached by using MMS for primary BCC with an infiltrative growth pattern.