Primary Extraosseous Ewing Sarcoma of the Orbit

Abstract

A 40-year-old man presented with painless, progressive vision loss and mild proptosis of the OD. CT revealed a right intraconal mass with slight penetration of the optic canal not contiguous with any bony structure. Incisional biopsy through a transfrontal orbitotomy revealed a diffuse growth of homogeneous, small, round cells. Immunohistochemical stains were positive for vimentin and MIC2 (CD99), and the translocation at EWS gene (22q12) was detected. Metastatic workup and a full-body bone scan were negative, confirming primary orbital extraosseous Ewing sarcoma. The patient received neoadjuvant chemotherapy and an orbital exenteration with preservation of eyelids and conjunctiva. He also received adjuvant chemotherapy and local radiotherapy, and he has remained disease-free for almost 3 years.