| Brown tumor | |
|---|---|
 | |
| Brown tumours of the hands in a patient with hyperparathyroidism. |
The brown tumor is a bone lesion that arises in settings of excess osteoclast activity, such as hyperparathyroidism. They are a form of osteitis fibrosa cystica. It is not a neoplasm, but rather simply a mass. It most commonly affects the maxilla and mandible, though any bone may be affected.[1] Brown tumours are radiolucent on x-ray.