The dual pathway of nevogenesis

The evolution of melanocytic nevi is a complex, multifactorial process involving both constitutional and environmental factors. While histopathology remains the gold standard for diagnosis of melanocytic lesions, it is a mere cross-sectional view of nevus evolution at one point in time. Dermoscopy and more recently, reflectance confocal microscopy (RCM) are in vivo diagnostic techniques for the assessment of morphologic features of nevi; the fact that most dermoscopic features are well correlated with histopathologic criteria makes these methods valuable for observing gross tissue changes of nevi over time without need to biopsy (Table 4.1). Thus, dermoscopy and RCM have enriched profoundly our knowledge about the morphological variability of nevi and offered new insights into their evolution.