Changing manifestations of brown tumors on bone scan in renal osteodystrophy.

In a patient with chronic renal failure and secondary hyperparathyroidism, brown tumors, visualized initially as photon-deficient areas on bone scintigraphy, reverted to areas of abnormally increased activity following parathyroidectomy. This dual appearance on bone scan paralleled the functional state of the parathyroid gland. The possible relationship of hyperhosphatemia to the increased bone-scan activity noted in the calvarium, mandible, and facial bones is discussed.