Brown tumor of bone: a potential source of false-positive thallium-201 localization

Brown tumor of bone (osteitis fibrosa cystica) should be included in the differential diagnosis of lesions that cause false-positive thallium-201 localization in patients with primary hyperparathyroidism. We report a case of a brown tumor of the upper sternum mimicking a superior mediastinal parathyroid neoplasm in a patient with persistent hyperparathyroidism 9 years after a negative neck exploration (with subtotal thyroidectomy and thymectomy). A 201TI/99mTc pertechnetate subtraction scintigram demonstrated complete subtraction of this 201TI focus.