Diagnostic dilemma in a case of eccentric proptosis in a 3 year old boy

A 3year-old boy presented to us with a painless proptosis in left eye.There was no clinical evidence of any systemic disease. Based on clinical and radiological investigations we arrived at the differential diagnosis of a hemangioma , venolymphatic malformation or rhabdomyosarcoma . We started him on steroids , initially patient responded to treatment but increase in proptosis was noted three months later. So we went ahead with left lateral orbitotomy and incisional biopsy of the tumour . Both histopathology (small round blue cell tumour) and immunohistochemistry (CD99 positivity) established the diagnosis of Extraosseous Ewing sarcoma. Patient was managed with surgical excision, chemotherapy ,postoperative adjuvant radiotherapy. Fifteen months after the initial presentation ,patient is tumour free and is on regular follow up.Although rare, Ewing sarcoma should be included in the differential diagnosis of uniform round cell orbital tumors. This article reports a rare case of extra osseous Ewings sarcoma of the orbit in a 3 year old boy and discusses the role of immunohistochemistry for the diagnosis and the multi modality approach of treatment that saved the patients life.