Rib-Origin Ewing Sarcoma With Cranial Nerve Involvement From Orbital Metastasis: A Rare Case Report.

Ewing sarcoma (ES) is an aggressive tumor of the bone in young adults, commonly originating from the pelvis and long bones. It is characterized by chromosomal translocation t(11;22) (q24;q12), resulting in the EWSR1-FLI1 fusion gene. It presents with metastasis commonly to the lungs and other soft tissues. While the metastasis to lungs is common, orbital involvement with cranial involvement is exceptionally rare. The case highlights the need for the early detection and aggressive treatment in order to reduce mortality in patients ES. A 23-year-old South-Asian male presented with a 2 month history of progressive shortness of breath, 10 × 15 cm swelling on the left side of chest, and left-sided proptosis with diplopia. The early examination of the patient showed left-sided pleural effusion and ophthalmoplegia involving cranial nerves II, III, IV, VI, and V1. Computed Tomography (CT) identified a rib-origin mass extending into the pleura, and Magnetic Resonance Imaging (MRI) confirmed an orbital mass compressing the optic nerve. Pleural fluid analysis showed an exudative, lymphocyte-predominant picture with elevated Adenosine Deaminase (ADA), initially mimicking tuberculosis. However, a CT-guided biopsy of the chest mass confirmed small round blue cell histology. Immunohistochemistry (IHC) was positive for CD99 and NKX2.2 with a high Ki-67 index, confirming Ewing sarcoma. The patient was initiated on multimodal chemotherapy but succumbed to rapid disease progression and respiratory failure 2 months post-diagnosis. ES is a highly aggressive bone tumor. Early diagnosis with subsequent aggressive treatment particularly is very important for the survival of the patient. Immunohistochemistry can be helpful in the diagnosis of the tumor, especially in resource-limited countries. Timely intervention is important in Ewing sarcoma owing to the risk of metastasis. Radiation, chemotherapy, and surgical interventions can be used depending upon the patient's prognosis.