A Rare Case of Melanotic Neuroectodermal Tumor of Infancy: Histopathological and Immunohistochemical Features

Melanotic neuroectodermal tumor of infancy (MNTI) is a rare, pigmented neoplasm of neural crest origin occurring predominantly in infants under one year of age. Although histologically benign, it exhibits locally aggressive behavior and can mimic malignancy due to rapid growth and bone destruction. Early recognition is essential for appropriate management. Case Report: We present a case of a 3-month-old male infant from Uttar Pradesh who presented with a bluish intraoral swelling involving the left side of the mandible. Computed tomography revealed a well-defined expansile lesion with mild enhancement in the body of left mandible. Serum vanillylmandelic acid (VMA) levels were within normal limits. Histopathological examination showed a biphasic tumor composed of large melanin-containing epithelial-like cells and small neuroblast-like cells arranged in nests and alveolar patterns. Immunohistochemistry demonstrated positivity for HMB-45, CD-99 and synaptophysin whereas S-100, desmin and WT1 were negative. A final diagnosis of melanotic neuroectodermal tumor of infancy was rendered. Complete surgical excision was performed, and postoperative recovery was uneventful. The patient remains under follow-up with no recurrence to date.MNTI is an uncommon but distinct entity that should be considered in the differential diagnosis of pigmented maxillary swellings in infants. A combination of histopathological and immunohistochemical findings is crucial for accurate diagnosis. Early surgical intervention with adequate margins provides an excellent prognosis.