Presurgical curettage appropriately reduces the number of Mohs stages by better delineating the subclinical extensions of tumor margins.

BACKGROUND: Whether presurgical curettage (PC), light curettage performed before Mohs surgery to delineate tumor margin, is appropriate or causes unnecessary removal of normal tissue has not been well established. OBJECTIVE: We aim to determine histologically whether PC appropriately increases the size of the stage I specimen or causes unnecessary removal of healthy tissue. METHODS: Before a surgical margin guided by PC was taken, a hypothetical margin determined by visual and tactile assessment alone (no curettage [NC]) was marked outside the clinically defined tumor. Histologic analysis at the NC and the PC margins revealed whether the increase in the stage I specimen as a result of PC was appropriate. RESULTS: PC appropriately increased the stage I specimen in 21 cases and unnecessarily removed normal tissue in only 1 case. The estimation of tumor margins with PC was 15 times more accurate than with NC (p value = .0012). CONCLUSION: For basal cell and squamous cell carcinomas at least 4 mm in diameter, light curettage performed prior to Mohs surgery could better delineate subclinical extensions of the tumor margin and appropriately increase the size of the stage I specimen.