Diagnostic accuracy of pigmented labial macules by in vivo reflectance confocal microscopy and correlation among techniques

Background: Pigmented labial macules (PLMs) are clinical, dermoscopic, and histopathologic challenges. Objective: To describe and evaluate the utility of reflectance confocal microscopy (RCM) in PLMs and to establish a correlation between dermoscopy, RCM, histopathology, and immunohistochemistry. Methods: Prospective study of PLMs from 4 tertiary referral dermatology centers. The study included 51 biopsy specimen-proven PLMs. Dermoscopic, RCM images, and histopathologic preparations were evaluated for malignant criteria. Diagnostic accuracy of RCM for melanoma diagnosis, RCM Lip Score previously reported, and k values between techniques were calculated. Results: Included were 5 melanomas and 46 benign PLMs. Dermoscopically, melanomas exhibited more frequently >= 3 colors and >= 3 structures. With RCM, pagetoid spreading, epithelial disarray, continuous proliferation of atypical cells around papillae, nonhomogeneously distributed papillae, marked cellular atypia, and a higher number of dendritic cells per papillae were more frequent in melanomas. The RCM Lip Score was significantly higher in malignant lesions. Good k values were observed in most of the evaluated features. A perfect sensitivity and specificity was obtained combining dermoscopy and RCM. Limitations: A low number of melanomas were obtained. Conclusions: RCM improves lip melanoma diagnosis, and the RCM Lip Score represents a useful tool for the evaluation of a PLM.