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.