Stress fractures associated with osteosarcoma of the lower limb.

Three patients with osteosarcoma of the femur developed abnormal radiopharmaceutical uptake in the bones of the contralateral leg. This uptake was not due to metastases. The histology in one patient, the form of the lesion and the disappearance of the abnormal uptake without treatment in the other two, indicated that the uptake was probably due to stress fractures. Changes in weight bearing and walking in the normal leg as a result of the osteosarcoma in the other leg could have been the cause of the stress fractures. It should be recognized that new abnormal uptake on bone scintigraphy in patients with osteosarcoma of the leg may not necessarily indicate metastasis. It may be caused by a stress fracture and disappears after rest.