RESUMEN
Radiation therapy is used for the palliative treatment of malignant tumors and the radiation induced osteonecrosis is one of the well documented complications. Especially, in pelvic region, there are a few reports for osteonecrosis of the femoral head and acetabulum after the radiation therapy for the the malignant tumors such as cervical carcinoma or prostatic cancer. Roentgenographic changes that are caused by radiation include the rarefaction of bone and coarsening of the trabeculae. The radiolucencies tend to coalesce and patchy sclerosis appears. In acetabular region, this Pagetoid appearance mimics the findings of other malignant bone tumors, the recurrence of preexisting malignant peivic tumors and other infectious condition. After the diagnosis is confirmed, the treatment for the femoral head and acetabulum is also difficult. The authors report one case of osteonecrosis of the femoral head and acetabulum following radiation therapy which had many difficulties in its diagnosis and treatment.