CO2 Laser Unroofing Reveals a Wider BCC-Compatible Field Beyond the Clinically Visible Margin: Dermoscopy and LC-OCT Findings in a Single Case

This single-case report examines dermoscopy-indexed peripheral line-field confocal optical coherence tomography (LC-OCT) reassessment during carbon dioxide (CO2) laser unroofing of a clinically suspected basal cell carcinoma (BCC). The proposed imaging contribution is the use of phase-related peripheral morphology to inform treatment-field reassessment. A 72-year-old woman with a 6 × 5 mm lesion on the right side of her back declined surgery and topical therapy. Three non-fractionated passes were performed. Manual planimetry showed a visible altered surface field that was 30.3% larger after the first pass and 14.3% larger after the second one relative to the baseline. BCC-compatible morphology was not identified in four untreated peripheral sectors approximately 1 mm beyond the visible margin at baseline, but it was detected in all four clinically corresponding sectors after the second pass. This prompted field enlargement before the planned final pass. No compatible morphology was identified in the selected final fields. Visual follow-up showed a resolving eschar at two weeks and a scar at six months. These observations do not validate tumor identity, histological margins or eradication; optical, thermal and sampling-plane effects remain possible explanations. Prospective case series with histological correlation should validate reproducibility and any clinical benefit of this proposed imaging application.