Case report 391: Postradiation necrosis of bone (femur) with no evidence of tumour

The case has been presented of a 21-year-old man who had been treated for Ewing tumor of the femur with local radiation and chemotherapy ten years previously. Significant increased uptake on the angiogram, blood pool studies and delayed imaging phases of the radionuclide scan was observed. This activity had increased dramatically from the bone scan obtained four years previously. Plain roentgenograms showed a mixed sclerotic and lytic lesion in the femur compatible with radionecrosis, recurrent Ewing tumor or radiation-induced osteosarcoma. Based on the findings of the bone scan a tumor was diagnosed and the patient underwent open biopsy. However, radiation osteonecrosis only was present; recurrent Ewing tumor or osteosarcoma was not observed. It may thus be stated that radiation can cause significant increase in uptake on serial bone scans even many years following radiation therapy. These features may simulate recurrent tumor or osteosarcoma. Thus, radionuclide bone scans, even many years after irradiation therapy, will not reliably differentiate between radiation-induced osteosarcoma, recurrent tumor or radiation osteonecrosis in patients who have been treated previously with radiation. (orig.)