Brown tumor of the orbit associated with primary hyperparathyroidism.

A 70-year-old woman had swelling of her left superior orbital ridge. A tumor was surgically removed, and histologic examination disclosed a tumor containing giant cells. Subsequent tests showed primary hyperparathyroidism caused by a carcinoma of the parathyroid. This rare instance of brown tumor of the orbit led us to review the differential diagnoses of giant-cell lesions of the orbit and to examine published case reports. Laboratory determinations of serum calcium, phosphorus, and alkaline phosphatase levels for all patients with lytic orbital bone lesions can establish whether they have hyperparathyroidism, a diagnosis making orbital surgery unnecessary.