Detection of hypervascular brown tumors on three-phase bone scan

A patient with hyperparathyroidism secondary to chronic renal failure had multiple bony lesions with increased activity on both immediate static as well as delayed scintiphotos. One lesion in the distal femur was also exceptionally hot on the flow phase. Plain radiographs demonstrated lytic lesions with sclerotic margins and a narrow zone of transition. Open biopsy revealed histology consistent with brown tumor (osteoclastoma).