[Melanoma on congenital nevus. Malignant differentiation after radiotherapy?]

Giant congenital nevi involve an approximately 5% risk of malignant transformation. We report about a 27-year-old patient who developed malignant melanoma after radiation of a large congenital nevus of the foot which was initially misinterpreted as a trophic disorder. The mechanisms and probability of malignant transformation and prophylactic therapy of large vs small congenital nevi are discussed.