Highly aggressive brown tumour of the maxilla as first manifestation of primary hyperparathyroidism.

A case is presented of a 62-year-old man with a right maxillary swelling for the previous three months. The lesion was expansive and osteolytic, with invasion of the adjacent maxillary sinus, nasal and pterygomaxillary fossae and floor of the orbit. Histology revealed the presence of an intrabony giant cell lesion. Blood tests demonstrated elevations in calcium (16.2 mg/dl) and parathyroid hormone (PTH) concentrations (841 pg/ml). This suggested the diagnosis of hyperparathyroidism initially manifesting as a brown tumour of the maxilla. Posterior explorations confirmed the existence of an underlying ectopic parathyroid adenoma as the cause of the condition.