Orbital Ewing's sarcoma of the orbit.

PURPOSE: Ewing's tumor is a primary tumor of bone in childhood that only rarely involves the orbit. Most such cases are metastatic from distant sites. This tumor may be confused with other small round cell malignancies of childhood, and immunohistochemical studies are essential in making the diagnosis.

METHODS: We present two cases of Ewing's tumor of the orbit. One was in a 22-year-old boy with an occult primary tumor in the frontal bone that became symptomatic after forehead trauma. The other example was in a 7-year-old boy with a known Ewing's primary of the clavicle. The clinical manifestations and diagnostic criteria are discussed.

RESULTS: In most cases with orbital involvement, ophthalmic symptoms consist of proptosis, pain, and occasionally visual loss and motility restriction. The diagnosis is typically unsuspected before histologic evaluation. Electron microscopic and immunohistochemical analyses are essential in making the diagnosis and are necessary for all such small round cell tumors.

CONCLUSIONS: Ewing's sarcoma is a rare orbital tumor of bone mainly affecting children. Local treatment relying on surgical extirpation and radiotherapy alone has proven inadequate, with 5-year survival rates of <10%. The addition of chemotherapy has improved survival rates significantly to approximately 50%.