Giant Pigmented Nevus
An irregular dark brown to black plaque over at least 5% of the body surface represents a gaint pigmented nevus. Often the lesions are of such size as to cover the entire trunk (bathing trunk nevi). Histologically, they are compound nevi. Transformation to malignant melanoma has been reported in as many as 10% of cases in some series, although the true incidence is probably much lower. Malignant change may occur in the neonatal period or at any time thereafter.