Extraskeletal Ewing's sarcoma arising in the nasal fossa. Light- and electron-microscopic observations.

Extraskeletal Ewing's sarcoma is a rare malignant neoplasm that has been reported to involve most frequently the soft tissues of the lower extremity and the paravertebral region. This report describes the clinicopathologic features of a polypoid tumor arising from the soft tissue of the left middle turbinate in a 39-year-old man. Histologically, the neoplasm was composed of small, round to oval cells with scant cytoplasm that were arranged in sheets with multiple areas of hemorrhage and necrosis. The cytoplasm contained glycogen granules. Electron microscopy revealed cells with scant cytoplasm containing glycogen rosettes and a paucity of organelles. These histologic and ultrastructural features are those of both skeletal and soft-tissue Ewing's sarcoma.