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Moles Atypical nevi – Incidence

Atypical nevi are common, with a prevalence estimated at 5-20%. While solitary atypical nevi are common, the familial syndrome is uncommon. The incidence of sporadic (non-familial) occurrence of multiple atypical nevi is unknown. Males and females are equally affected. Atypical nevi are not present at birth and begin to appear during early childhood. The characteristic features of atypical moles are present at the time of puberty. Unlike common acquired melanocytic nevi, which stop appearing after age 30, atypical nevi continue to appear well into adulthood. While sun exposure does appear to favor the appearance of atypical nevi, lesions develop in both sun-exposed and sun-protected areas. The number of nevi varies in patients with multiple atypical nevi. Most affected people have more than 50 melanocytic nevi, some of which are atypical in appearance. There is striking heterogeneity from one nevus to another.