Giant hamartomatous nevus of undescribed complexity (development of an infiltrating malignant melanoma)

A case is reported of complex hamartoma with the aspect of a giant pigmented nevus, localized in one of the lower extremities. Histological examination revealed the involvement of different embryonal layers in order to give rise to dissimilar types of nevi: flat pigmented nevus, intradermal cellular nevus, epidermal verrucous nevus, Jadassohn's sebaceous nevus; Hoffman-Zurhelle's superficial lipomatous nevus, and fibrous hamartoma of the manifested at infancy. This malformation and more specifically the nevus cells constitute the subsequent transformation into an infiltrating malignant blastoma (malignant melanoma).