Discoid Lupus Erythematosus: A Comparative Evaluation Between Line-Field Confocal Optical Coherence Tomography and Histology in a Multicenter Cross-Sectional Study

: Discoid lupus erythematosus (DLE) is the most common variant of cutaneous lupus. Histopathology remains the gold standard for diagnosis, but it carries a risk of scarring in a disease already prone to cicatricial outcomes. Additionally, diagnostic delays may occur due to variable processing times, particularly in challenging cases. Line-field confocal optical coherence tomography (LC-OCT) is a novel non-invasive imaging technique offering high-resolution, histology-like features. This study evaluates its diagnostic accuracy in DLE by assessing concordance with histopathology. A cross-sectional study enrolled histologically confirmed DLE from three tertiary referral hospitals. Eleven histological criteria were assessed using LC-OCT and subsequently compared to histopathology. Concordance was evaluated using Cohen's Kappa coefficient (K), with McNemar's test applied to detect significant differences (α = 0.05). Twenty-eight patients with DLE participated in the study. LC-OCT demonstrated strong agreement with histopathology in key diagnostic features of DLE. Near-perfect concordance (K = 1, 100% agreement) was observed for interface dermatitis, dermal vessel dilation, epidermal atrophy, and incontinentia pigmenti. Substantial agreement was found for epidermal disarray (K = 0.85), spongiosis (K = 0.70), necrotic keratinocytes (K = 0.70), and infundibular dilation (K = 0.79). Overall, LC-OCT achieved a Cohen's Kappa of 0.74 with 87.66% concordance, and no statistically significant differences were observed between the two methods (McNemar p = 0.627). LC-OCT is a rapid, effective, and non-invasive diagnostic tool for DLE, demonstrating strong concordance with histopathology and potential for early diagnosis and clinical implementation.