Nevi and melanoma: lessons from Turner's syndrome.

Females with Turner's syndrome (TS) have a markedly increased number of cutaneous nevi. While this is a well-recognized risk factor for cutaneous melanoma (CM), the incidence of this tumor in TS and the implications for our understanding of nevi and melanoma have not previously been considered. Here we report a case of an anorectal melanoma in a woman with TS and a review of the literature. Overall, there appears to be a lower than expected incidence of CM. Possible explanations are discussed and in particular the possible relationship between sex hormones and melanoma development as these girls fail to undergo normal pubertal development. Further study of this syndrome may provide important insights into the genetic factors involved in normal melanocyte and nevus development, the potential influence of sex hormones on melanoma development and the relationship between the presence of nevi and the risk of developing CM.