Ewing’s Sarcoma of the Hip Presenting as a Benign Cystic Lesion

A 14-year-old girl with a Ewing’s sarcoma of the left femoral head and neck is presented. The imaging features mimicked a benign cystic lesion. Biopsy and molecular analysis confirmed the diagnosis. The patient was treated with chemotherapy, wide tumor resection, and proximal femoral reconstruction using an allograft–prosthesis composite. Differential diagnosis, imaging, and pathologic features of Ewing’s sarcoma are discussed. (Journal of Surgical Orthopaedic Advances 16(2):84–88, 2007)