Primary Ewing's sarcoma of the sphenoid bone with unusual imaging features: a case report.

Ewing's sarcomas (ES) account for approximately 10% of primary malignant bone tumors. Primary Ewing's sarcoma of the skull is a very rare entity. We report a case of Ewing's sarcoma of the sphenoid bone in a 5-year-old boy. CT scan showed heterogeneously enhancing mass with associated spiculated new bone formation along the posterolateral wall of the orbit. Magnetic resonance (MR) imaging showed markedly heterogeneously signal intensity mass lesion containing areas of hemorrhage and fluid-fluid levels. Spiculated new bone formation and fluid-fluid levels had not been reported previously in skull Ewing's sarcomas and may be helpful features for preoperative diagnosis.