Multiple brown tumors of the ribs simulating malignancy.

Bone disease associated with primary hyperparathyroidism, known as osteitis fibrosa cystica, is now very rarely encountered, since the parathyroid disorder is most often diagnosed at the early stage of asymptomatic hypercalcemia. Here, we report the case of a patient with multiple pleural-based masses and hypercalcemia, which led to the presumptive diagnosis of malignancy. However, histological and laboratory data were consistent with the development of brown tumors of the ribs due to underlying severe hyperparathyroidism.