Clinical and immunohistochemical study of melanotic neuroectodermal tumor of infancy in the maxilla.

Melanotic neuroectodermal tumor of infancy is a rare and fast-growing neoplasm. In this study, we describe the case of a 6-month-old female patient, who presented swelling in the anterior maxilla. Tomographic reconstruction showed an unilocular hypodense and expansive area associated with the upper right central primary incisor. The presumptive diagnoses were dentigerous cyst, adenomatoid odontogenic tumor, melanotic neuroectodermal tumor of infancy and rhabdomyosarcoma, and an incisional biopsy was performed. Microscopically, the lesion revealed a biphasic cell population, consisting of small, ovoid, neuroblastic-like cells and epithelioid cells containing melanin. Immunohistochemically, the melanocyte-like component was strongly and diffusely positive for HMB-45 and Melan-A, but weakly positive for S100. Based on these findings, definitive diagnosis of melanotic neuroectodermal tumor of infancy was established. Then, enucleation of the lesion was performed by careful curettage. After 2 year follow-up, no clinical or radiographical evidence of recurrence was verified. The present case highlights the importance of early diagnosis and therapeutic intervention at the appropriate time to achieve a favorable outcome for the patient.