melanoma non-cutaneous melanoma extracutaneous melanoma UMLS:C1334974 NCIT:C8711 EFO:1000397 MEDGEN:233761 MONDO:0006320 non-cutaneous melanoma Melanoma is a malignant tumor of melanocytes, cells that are derived from the neural crest. Although most melanomas arise in the skin, they also may arise from mucosal surfaces or at other sites to which neural crest cells migrate. (PDQ)