Accuracy of Confocal Microscopy for the Diagnosis of Acral Lentiginous Melanoma and Acral Melanocytic Nevi

Acral lentiginous melanoma (ALM) is a highly malignant skin tumor that is often difficult to differentiate from acral melanocytic nevi (AMN), potentially delaying diagnosis. Reflectance confocal microscopy (RCM) is a noninvasive imaging technique that produces images consistent with histopathology. However, few studies have reported on the use of RCM for the differential diagnosis of ALM and AMN. This study aimed to assess the diagnostic accuracy of RCM in differentiating ALM from AMN. This retrospective study analyzed the RCM features of ALM and AMN, assessed concordance with histopathology using Cohen kappa coefficient, and evaluated the diagnostic accuracy of RCM. Receiver operating characteristic curve analysis was also performed to assess overall diagnostic performance. ALM and AMN exhibited distinct RCM features. RCM showed high concordance with histopathology (Cohen kappa = 0.799, P < 0.001). The diagnostic accuracy of RCM was 90.3%, with a sensitivity of 91.7%, specificity of 89.5%, and an area under the curve of 0.906 (95% CI: 0.820–0.992, P < 0.001). RCM is a reliable, noninvasive tool for differentiating ALM from AMN, and may help guide clinical decision making.