ABSTRACT
Congenital nevi are a group of skin lesions occurring at birth or becoming apparent within the first several years of life, and are characterized by ectopic rests of dermal elements. Although most commonly melanocytic in nature, nevi may also originate from sebaceous, neural, or epidermal elements. Congenital melanocytic nevi (CMNs) are the most common congenital nevi and are composed of cells of melanocytic origin that carry a varying amount of pigment. These are usually present at birth, though a small percentage may not initially be evident due to a lack of pigment production. The overall incidence of CMN is estimated to be 1"-6" of live births, with larger lesions being much less common. Embryologically, melanocytes originate from neural crest cells as melanoblasts and migrate to the basal layer of the epidermis between the 5th and 24th week of gestation. In contrast with normal melanocytes, nevus cells tend to group together in clusters and assume a rounded rather than dendritic shape.
