ABSTRACT
Most osteosarcomas arise spontaneously, but rarely they may be secondary to other benign osseous conditions and may occur following irradiation. Postradiation sarcoma of bone is approximately 5.5 percent of all osteogenic sarcoma. Diagnosis is possible when a sarcoma arising after long latent period(more than 3 years) in irradiated bone and the bone is normal or benign osseous lesion at the time of irradiation. The spontaneously arising osteogenic sarcomas are distribute mainly in the knee region, but postradiation sarcoma arise in any bones, such as long bone of the extremity, pelvic bone, vertebra, craniofacial bone and shoulder girdle bone. Recently we experienced a case of postradiation osteosarcoma of the pelvic bone who received radiation therapy for carcinoma of the uterine cervix 20 years ago.