Brown tumor of the rib as a first presentation of primary hyperparathyroidism: Report of three cases and literature review.

A brown tumor is a non-neoplasm mainly caused by hyperparathyroidism. It often occurs in the pelvis, ribs, long bone shaft, clavicle, and jaw. We introduce three cases of primary hyperparathyroidism, with the first symptom of brown tumor of the ribs, and discuss the image characteristics within the literature. We then propose the value of ultrasound in the diagnosis of brown tumor.