Ewing sarcoma of the orbit: An unusual presentation
The present case has been published in the journal Ophthalmology.

A 10-year-old boy presented with progressive left-sided proptosis. Magnetic resonance imaging revealed a heterogeneous, left sphenoid bone mass extending into the orbit, and middle cranial fossa comprised of multi-cystic spaces with fluid-fluid levels appearing hyperintense on T2-weighted images (Fig 1A-B).

The differential diagnosis included a neoplasm of mesenchymal origin, aneurysmal bone cyst, giant cell tumor, and metastatic neuroblastoma. Histopathology of the orbital biopsy demonstrated small round cells with monotonous nuclei (Fig 1C, H&E stain, 400×) that stained positive for CD99 and FLI-1.

Fluorescence in-situ hybridization revealed the EWSR1 (22q12) gene rearrangement (Fig 1D), confirming Ewing sarcoma. The patient completed chemotherapy and radiotherapy (AEWS0031 Regimen B). At 1-month posttreatment, he is expected to have an event-free survival of 73% at 5 years.

Source: https://www.aaojournal.org/article/S0161-6420(18)31314-9/fulltext
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