Flare phenomenon in osteosarcoma after complete remission.

A patient undergoing cytostatic therapy for osteosarcoma of the right humerus had bone scans at 2-mo intervals. A skeletal focus of increased radiotracer accumulation occurred and subsequently was confirmed by CT and MRI. A necrotic metastasis was found during biopsy. There were no remaining viable tumor cells. This finding confirms the presence of the flare phenomenon in skeletal metastases in primary malignant bone tumors and that radionuclide imaging may fail to detect intramedullary foci of viable metastases in these tumors.