Giant congenital neuroid melanocytic nevus.

A patient with a variety of nevus cell nevi, a congenital giant melanocytic nevus, abnormal facies, vascular anomaly of the leg, and mental retardation was examined. The patient also had neuroid elements within the giant nevus that led to the consideration of neurofibromatosis. Because neurofibromatosis is a genetically determined condition with tissue different from the neuroid elements seen in giant nevi, the two conditions are considered to be different entities. Malignant transformation of congenital giant pigmented nevi occurs, although the incidence of such transformation remains a subject of controversy.