Reflectance Confocal Microscopy Versus Line‐Field Confocal Optical Coherence Tomography in Facial and Scalp Lesions Suspicious for Basal Cell Carcinoma: A Histopathology‐Referenced Multi‐Reader Study

Background Non-invasive imaging techniques can support assessment of lesions suspicious for basal cell carcinoma (BCC) when dermoscopy is inconclusive. We compared reflectance confocal microscopy (RCM), line-field confocal optical coherence tomography (LC-OCT), and the device-integrated LC-OCT artificial intelligence (AI) output. Methods This retrospective comparative observational study included 100 facial and scalp lesions evaluated by RCM and LC-OCT before excisional biopsy. Two expert and two non-expert dermatologists independently interpreted anonymized images while blinded to histopathology and recorded confidence on a four-point scale. Diagnostic performance, inter-reader agreement, reader-specific receiver operating characteristic analyses, and an exploratory post hoc dermoscopically equivocal subgroup were assessed. The categorical AI output was analyzed at a single operating point. Results Histopathology identified 69 basal cell carcinomas (BCCs) and 31 non-BCC lesions. Expert mean sensitivity, specificity, and accuracy were 95.7%, 85.5%, and 92.5% for RCM versus 86.2%, 67.7%, and 80.5% for LC-OCT. The AI output yielded 87.0% sensitivity, 83.9% specificity, and 86.0% accuracy. In the equivocal subgroup (n = 51; 31 BCCs), RCM sensitivity was 96.8% across readers, with specificity ranging from 65.0% to 85.0%. RCM AUCs exceeded LC-OCT AUCs for all readers, but no paired comparison remained significant after Holm adjustment. Inter-reader agreement was higher for RCM than LC-OCT (Fleiss' κ = 0.809 vs. 0.563). Conclusions Both modalities provided diagnostic information as second-level adjuncts. RCM showed higher observed performance and agreement, particularly in exploratory equivocal lesions, whereas the categorical LC-OCT AI output showed comparatively high specificity. Prospective validation is required.