Benign or Malignant? Ex Vivo Confocal Laser Scanning Microscopy for Bedside Histological Assessment of Melanocytic Lesions

Objective: Ex vivo confocal laser scanning microscopy (EVCM) is an emerging imaging technique, which offers rapid tissue examination. While the current literature shows promising results in the evaluation of non-melanoma skin cancer, only limited research exists on the application of EVCM in melanocytic lesions. This study aimed to assess the utility of EVCM in the characterization of melanocytic lesions and compare its findings with gold-standard histopathology. Methods: A total of 130 skin lesions, including 76 benign and 54 malignant melanocytic lesions, were prospectively collected and imaged using EVCM. Three blinded investigators were asked to identify characteristic morphologic features observed in the lesions and classify them into benign vs. malignant. The results were then compared with the corresponding histopathology. Sensitivity and specificity were calculated using contingency tables to assess the diagnostic performance. Results: The application of EVCM allowed for the visualization of cellular and tissue-level details, including cellular pleomorphism and atypical melanocytes. A comprehensive list of benign and malignant features identified by EVCM was compiled. Using these diagnostic criteria, the imaging of the inexperienced and dermatohistopathology-experienced investigator reached 67.7% concordance, and the imaging trained dermatologist obtained 69.2% agreement with dermatohistopathology in differentiating benign vs. malignant lesions. The imaging-trained dermatohistopathologist performed best with concordance up to 79.2%. Conclusions: In conclusion, EVCM is a promising technique for the rapid assessment of melanocytic lesions. Our study provides a comprehensive overview of morphologic EVCM features, which will contribute to the development of diagnostic algorithms for accurate diagnosis and appropriate treatment planning. Further studies are needed to evaluate its clinical utility and validate our diagnostic criteria.