Primary Orbital Ewing Sarcoma Presenting with Optic Neuropathy and Rapid Proptosis in an Adolescent Girl

Abstract Primary orbital Ewing sarcoma (POES) is an exceptionally rare and aggressive malignant tumor, particularly in the pediatric population. We report the case of a 14-year-old girl who presented with progressive right eye proptosis, visual disturbances (finger counting at 2 m), headache, and vomiting over a 4-month period. Imaging revealed a mass involving both intraorbital and extraorbital compartments with signs of optic neuropathy. The patient underwent right frontotemporal craniotomy with subtotal debulking of the tumor. Histopathology and immunohistochemistry confirmed a diagnosis within the Ewing sarcoma family (diffuse CD99 and NKX2.2 positivity). Molecular confirmation for EWSR1 rearrangement by fluorescence in situ hybridization (FISH) or reverse transcription polymerase chain reaction (RT-PCR) could not be performed due to resource limitations. She received VAC/IE-based adjuvant systemic chemotherapy. At 6 months, the patient remained clinically stable with improved proptosis and visual function (right eye: finger counting at 6 m; left eye: 6/6), without clinical evidence of progression. The orbit is an extremely uncommon site for Ewing sarcoma, posing diagnostic and therapeutic challenges. This case reinforces the importance of early recognition, surgical decompression when vision is threatened, and coordinated multidisciplinary management; however, a 6-month follow-up is early and does not permit claims of durable remission or long-term oncologic control. To the best of our knowledge, POES remains exceedingly rare in the Asian subcontinent, with only a limited number of cases reported.