Mediastinal Extraskeletal Osteosarcoma
Extraosseous osteogenic sarcoma; Extraosseous osteosarcoma
Extraskeletal osteosarcoma is a malignant osteoid-producing soft tissue neoplasm that by definition is unattached to the bone or periosteum. Contrary to osteosarcoma of the bone which mainly affects adolescents and young adults, extraskeletal osteosarcoma is a disease of middle-aged and older adults which infrequently occurs in patients under the age of 40. Extraskeletal osteosarcoma is a rare malignancy that accounts for only 1–2% of all soft tissue sarcomas and for 2–4% of all osteosarcomas. It most commonly arises in the soft tissues of the lower extremities, especially the thigh but also in the buttocks, shoulder girdle, trunk, and retroperitoneum. Primary mediastinal extraskeletal osteosarcomas have been reported as isolated case reports; to date, less than ten cases have been published in the English literature (Hishida et al. 2009). Several hypotheses as to the histogenesis of these tumors exist...