Brown tumor of the patella caused by primary hyperparathyroidism: a case report.

It has been reported that the common sites of brown tumors are the jaw, pelvis, ribs, femurs and clavicles. We report our experience in a case of brown tumor of the patella caused by primary hyperparathyroidism. An initial radiograph and CT showed an osteolytic lesion and MR images showed a mixed solid and multiloculated cystic tumor in the right patella. One month after the parathyroidectomy, rapid bone formation was observed on both radiographs and CT images.