Extraskeletal osteosarcoma of abdominal wall in a child.

Compared with osteosarcoma of bone, extraskeletal osteosarcoma is rare and accounts for approximately 1% to 2 % of all soft tissue sarcomas. Osteosarcoma arising in soft tissues is exceedingly rare in children. The tumor most often affects older adults, involves the lower extremity, responds poorly to chemotherapy, and carries a grave prognosis. The authors describe a 4-year-old girl with an extraskeletal osteosarcoma in the lateral abdominal wall.