PLURIPOTENTIAL MELANOBLASTOMA, A UNIFYING CONCEPT ON MALIGNANCIES ARISING IN CONGENITAL MELANOCYTIC NEVI - REPORT OF 2 CASES

Congenital melanocytic nevi are benign lesions present at birth and co nsidered to be caused by a maldevelopment of the neural crest. The mal ignant potential of the congenital melanocytic nevi have been extensiv ely addressed by several authors, and malignant melanoma is the most f requent neoplasm arising these lesions. The present report describes t wo patients with congenital melanocytic nevi in which malignant melano ma with undifferentiated areas showing rhabdomyoblastic differentiatio n developed. The findings suggest that these mixed neoplasms may be re capitulating the differentiation potential of the ectomesenchyme-neura l crest cells. We advocate the term ''melanoblastoma'' when referring to them.