A rare case of adult presentation of an indolent orbital melanotic neuroectodermal tumor of infancy.

A 21-year-old female presented with a known left orbital mass. The mass was incidentally identified 5 years previously after a motor vehicle accident. After initial discovery, the lesion had been followed with surveillance imaging and remained radiographically stable, during which her only symptom was headache. Recent worsening periorbital pain, headache, and progressive visual decline prompted referral. At presentation, best corrected visual acuity was 20/40 in the left eye with 1+ relative afferent pupillary defect (RAPD). Updated imaging revealed a left intraconal orbital mass compressing the optic nerve. The lesion was approached via lateral orbitotomy with bone flap. The tumor was adherent to the optic nerve, and partial resection was achieved. Histopathology demonstrated a biphasic neoplasm consistent with melanotic neuroectodermal tumor of infancy (MNTI). We report a very rare congenital neoplasm with delayed presentation and slow growth rate.