Mohs micrographic technique in high-risk basal cell carcinoma: a 3D prediction of safety margins.

Objective: Compared with standard excision with a two-dimensional histological examination, Mohs micrographic surgery offers a lower recurrence rate and a greater extent of healthy tissue sparing for the treatment of high-risk basal cell carcinoma (BCC). The aims of this study were to first quantify the healthy tissue spared through the micrographic technique compared to traditional surgery for high-risk tumours. Then, to speculate, through the analysis of the distal micrographic resection margin, the adequate width of safety margins for standard excision.

Method: A cohort of patients with high-risk BCC was treated with Mohs surgery. Safety margins, tumours residual final breach and hypothetical standard excision safety margins areas were recorded.

Results: A total of 96 patients were included. A reduction of 27.96% (95% Confidence Interval (CI): 17.90-38.02) of healthy skin removed was observed using a micrographic method compared to the standard approach. Standard excision with a 6mm safety margin was associated with 86.46% (95% CI: 79.62-93.30) of complete excision. Greater margins were not associated with a statistically significant improvement of complete excision.

Conclusion: Mohs surgery should be considered the gold standard operative treatment for high-risk BCC. However, if micrographic techniques are not feasible, the standard excision with a predetermined margin of 6 mm, should be considered as the best option.