Maxillary brown tumor as initial presentation of parathyroid adenoma: a case report.

Brown tumor is a rare late-stage skeletal change caused by long-term stimulation of excess parathyroid hormone. It is not neoplastic, but a reparative cellular process. Common sites of brown tumor are the ribs, clavicle, long bones and pelvic girdle. Solitary maxillary brown tumor as initial presentation of primary hyperparathyroidism is rare; it is often accompanied by brown tumors of the other facial bones. Here, we present the first case of solitary maxillary brown tumor in a 29-year-old ethnic Chinese woman with initial presentation of a large tumor filling the left maxillary sinus. Underlying long-standing primary hyperparathyroidism caused by a large parathyroid adenoma was finally diagnosed. Brown tumor tends to be misdiagnosed as malignancy, and delayed diagnosis of the underlying hyperparathyroidism is common. Our case validates the suggestion that young women have a higher probability of brown tumor. Biopsy of the suspicious bone tumor and blood tests for calcium and parathyroid hormone level are crucial and essential to reach the correct diagnosis. Most brown tumors show spontaneous regression after parathyroidectomy. However, direct excision of the brown tumor may be indicated to avoid the risk of facial deformity and orbital compression at a special anatomical site, as in our case.