The risk of melanoma and neurocutaneous melanosis associated with congenital melanocytic nevi.

Congenital melanocytic nevi are commonly encountered in clinical practice. Although the development of malignant melanoma arising in small and intermediate congenital melanocytic nevi is rare, there is a significant risk of malignant degeneration associated with large congenital melanocytic nevi, in particular those that arise on the torso in the so-called "bathing trunk" distribution, where the risk is estimated to be about 2.5% to 5%. The risk of malignant melanoma arising within a large congenital melanocytic nevus is highest in the first 5 to 10 years of life and carries a significant mortality. Large congenital melanocytic nevi, in particular those overlying the posterior axis and occurring in the context of multiple satellite melanocytic nevi, are also associated with the development of neurocutaneous melanosis, which may result in neurologic and neurodevelopmental sequelae and is associated with a significant risk of primary central nervous system melanoma and death.