Brown tumor is a focal lesion of the bone caused by primary or, less commonly, secondary or tertiary hyperparathyroidism (HPT). While the mandible is the most frequently involved bone in the head and neck region, atypical involvement of the cranium in the area of the sphenoid sinus is exceedingly rare. In the literature, a unique case of brown tumor of the sphenoid sinus was reported in a patient with primary HPT. We present a case of sphenoid sinus and occipital bone brown tumor associated with primary HPT A 47-yr-old woman presented a 2-yr history of headaches, dizziness, diffuse body and articular pain, fatigue, and a 6-month history of intermittent nausea and vomiting, polydipsia, and polyuria. Magnetic resonance imaging (MRI) demonstrated an expansive mass lesion in the sphenoid sinus with erosion of the sellar floor and medial wall of the right orbit, and expansion in the medulla of bone. Examination of biopsy specimens obtained from sphenoid sinus mass confirmed the diagnosis of brown tumor. The biochemical laboratory studies showed elevation of parathyroid hormone and confirmed the diagnosis of primary HPT. Excision of a parathyroid adenoma affected the metabolic status into normalizing. At the follow-up of 12 months postoperatively, the size of sphenoid sinus brown tumor decreased and the mass of occipital bone disappeared. In conclusion, this is a first report of primary HPT masquerading as a destructive fibrous sphenoid sinus brown tumor associated with a mass lesion of occipital bone and hypercalcemia in the literature. (C) 2004, Editrice Kurtis.