Exploratory systematic characterization of vascular features in confocal laser endomicroscopy of cutaneous squamous cell carcinoma.

PURPOSE: This exploratory study aimed to systematically evaluate vascular features in confocal laser endomicroscopy (CLE) for distinguishing cutaneous squamous cell carcinoma (cSCC) from healthy skin, assessing both the overall diagnostic value of these features using a composite vascular scoring system and the performance of individual criteria. METHODS: CLE video sequences of tumor and corresponding healthy skin were retrospectively analyzed in nine patients, using histopathology as the reference standard. Six vascular criteria were defined from the literature, three associated with healthy tissue and three with tumor tissue. Three experienced investigators performed a blinded assessment, and a majority decision determined the presence of each criterion. Sensitivity, specificity, predictive values, and interrater agreement were calculated. A composite vascular score (0-6) was derived, and ROC analysis was used to determine the optimal cutoff for discriminating tumor from healthy tissue. RESULTS: The features with the highest diagnostic relevance were "honeycomb-like capillaries" and "round vascular structures" for healthy tissue, and "leaky capillaries" for tumor sequences. ROC analysis identified a cutoff of ≥ 3 (Youden index 0.905, AUC 0.96). Within the analyzed dataset, the composite vascular score achieved a sensitivity of 100%, specificity of 90.48%, PPV of 91.3%, and NPV of 100%. CONCLUSION: Vascular features captured by CLE showed promising discriminatory potential for differentiating cSCC from healthy skin. Among the individual criteria, absence of "honeycomb-like pattern" of capillaries and "round vascular structures" are particularly suitable for inclusion in a CLE-based scoring system for cSCC.