Dermoscopic and clinical predictors of reflectance confocal microscopy patterns of typical nevi on the back and legs: A cross-sectional study

Background: Nevus phenotype is a marker of melanoma risk. In vivo prediction of microscopic pattern is needed to more precisely classify nevi. Objective: To identify dermoscopic and clinical predictors of microscopic patterns of typical nevi. Methods: We used reflectance confocal microscopy (RCM) to classify microscopic patterns of nevi. We prospectively accrued adults presenting for periodic skin screening and imaged, with dermoscopy and RCM, 3 randomly selected nevi from the upper and lower back and lower extremity. RCM patterns were classified into ring, clod, meshwork, and composite types. Logistic regression was used to identify best predictors of RCM pattern. Results: The study included 310 nevi from 112 participants (mean age 44 years; 51 women). Dermoscopic reticular pattern correlated most frequently (59.9%) with RCM ring pattern, dermoscopic globular with RCM composite (56.6%) and RCM clod (35.9%), dermoscopic complex with RCM composite (76.3%), and dermoscopic homogenous with RCM clod (50.8%). Integrating dermoscopic pattern with contour, diameter, color, and anatomic location of nevi improved prediction of microscopic patterns beyond dermoscopy alone. The dermoscopic clinical regression model correctly classified lesions to RCM ring versus RCM clod in 90% and to RCM ring versus RCM composite patterns in 81%. Limitations: The study was restricted to adults, back and lower extremities, and typical nevi. Conclusions: Integrating dermoscopic patterns with clinical attributes may improve prediction of microscopic patterns of nevi.