Surgical Outcomes of Nonmelanoma Skin Cancer Managed with Systematic Preoperative Reflectance Confocal Microscopy-Guided Margin Assessment: A Retrospective Cohort Study Comparing Wide Local Excision and Mohs Micrographic Surgery.

Background

Reflectance confocal microscopy (RCM) enables noninvasive, high-resolution visualization of skin tumors and may improve preoperative margin assessment in nonmelanoma skin cancer (NMSC). However, its impact on surgical outcomes in routine clinical practice remains incompletely defined.

Objective

To evaluate surgical outcomes of NMSC managed with systematic preoperative RCM-guided margin assessment, comparing wide local excision (WLE) and Mohs micrographic surgery (MMS).

Methods

We conducted a retrospective study of 71 consecutive NMSC treated at a tertiary dermatologic oncology center. All tumors underwent RCM evaluation for diagnosis and preoperative margin mapping. Outcomes included positive margins after WLE, local recurrence, recurrence-free survival, and the number of Mohs stages. Associations were analyzed using Fisher's exact tests and Firth penalized logistic regression.

Results

Among 47 tumors treated with WLE, positive margins occurred in 10.6%. Among 24 MMS cases, 70.8% were cleared in a single stage. Local recurrence occurred in 14.9% of WLE-treated tumors and in none of the MMS-treated tumors (p = 0.087). All recurrences occurred in tumors initially demonstrated positive margins after WLE, despite subsequent re-excision and histologic clearance. In multivariable Firth regression, MMS was associated with a lower risk of recurrence (OR 0.13; 95% CI, 0.008-2.10).

Conclusions

In this RCM-guided cohort, low margin positivity after WLE and high single-stage clearance in MMS suggest improved surgical accuracy and efficiency. Recurrence was confined to margin-positive tumors, supporting a margin-driven model of tumor control and highlighting RCM as a potential preoperative margin-control strategy.