What is the risk of developing a malignant melanoma in a congenital nevus?

Although there is little agreement about the risk of developing melanoma within a CMN, some general guidelines can be stated. The risk appears to relate to the size of the CMN. A small or medium CMN does not appear to have any significantly greater risk for melanoma than an acquired melanocytic nevus. The best evidence suggests that there is about a 1% to 4% chance of developing melanoma in CMN >60 cm. The need for removal of congenital nevi is one of the most controversial issues in pediatric dermatology. It should be stressed that surgical removal of the CMN does not decrease their risk for melanoma.

Kinsler VA, Birley J, Atherton DJ: Great Ormond Street Hospital for Children Registry for Congenital Melanocytic Naevi: prospective study 1988–2007. Part 1— epidemiology, phenotype, and outcomes, Br J Dermatol 160:143–150, 2009.

Kinsler VA, Birley J, Atherton DJ: Great Ormond Street Hospital for Children Registry for Congenital Melanocytic Naevi: prospective study 1988–2007. Part 2—evaluation of treatments, Br J Dermatol 160:387–392, 2009.