RESUMEN
The melanotic neuroectodermal tumor of infancy(MNTl) is a rare, usually benign, pigmented lesion which most frequently involves the maxilla. Skull, brain, and mandible are other craniofacial sites; this anatomic region accounts for 87% of all cases. The vast majority of MNTl, nearly 95%, present in infants of both sexes within the first year of life. Most cases of MNTl follow a benign course, with a 15% propensity for local recurrence. MNTl is regarded as a primitive neuroectodermal tumor with polyphenotypic differentiation. We report a classical MNTl which occurred in left lower maxilla in 6-month old female infant. She developed an ill defined, firm swelling on the left alveolar ridge and gum during 3 weeks. Mass excision reveals ill defined, grayish-tan hard mass, measuring 2.0x1.6 cm. Microscopically, the tumor reveals irregular alveolar pattern of melanin-containing cuboidal cells and nests of small round cells. The immunohistochemical staining for melanoma-associated antigen, neuron-specific enolase and cytokeratin show positive reactions. Ultrastructural examination showed intracytoplasmic melanosome, tonofilament and desmosome.