Basal cell carcinomas (BCC) with high-risk features are preferably treated by Mohs micrographic surgery (MMS). Studies have shown clinicopathologic characteristics that may predict more stages required for clearance. However, few studies have correlated such factors with the number of millimeters removed per stage.
To determine margins necessary for BCC clearance based on tumor features, especially for tumors < 6mm, and to suggest initial margins for MMS and margins for WLE.
Retrospective analysis of 295 consecutive MMS. Variables analyzed included patient age, sex, immune status, lesion size, location, histologic subtype, borders, stage number, and millimeters excised per stage.
BCC < 6 mm had a clearance rate of 96% with 3-mm margins. In adjusted multivariable analysis, superficial, micronodular, infiltrative, and morpheaform subtypes were associated with larger margins; whereas clinically well-defined tumors were associated with smaller margins.
Due to limited sample of certain subtypes, the recommendation of 3-mm margin is better suited for nodular tumors.
This data helps guide initial MMS and WLE margins required for tumor clearance according to tumor features. Nodular BCC < 6 mm may be cleared with 3-mm margins instead of the current 4-mm margin recommendation.

Copyright © 2020. Published by Elsevier Inc.