Sphenoid sinus brown tumor, hypercalcemia, and blindness: an unusual presentation of primary hyperparathyroidism

This is a first report of primary hyperparathyroidism (HPT) masquerading as a destructive fibrous sphenoid sinus "Brown tumor" associated with progressive blindness and hypercalcemia. Diagnosis of a Brown tumor was delayed despite serial computerized tomography of the head and repeated transnasal and transethmoid sphenoid biopsies demonstrating diffuse fibrosis. Only detection and medical evaluation of hypercalcemia, demonstrating elevation of both serum calcium and C-terminal parathyroid hormone with an elevated chloride/phosphate ratio, prompted neck exploration, thus confirming a solitary left superior parathyroid adenoma. Postoperative normocalcemia occurred synchronously with the return of light perception and the arrest of sphenoid sinus and parasellar erosion. Although maxillary Brown tumors of secondary HPT have been reported, this is the first report of osteitis fibrosa of the sphenoid sinus. Differential diagnosis of an erosive sphenoid lesion with cranial nerve dysfunction, exclusive of inflammatory or vascular disease, should include sarcoidosis, primary and metastatic sphenoid carcinoma, fibrous dysplasia, giant cell reparative granuloma, midline lethal granuloma, chordoma, and chondrosarcoma. Furthermore, the bony destructive lesions with concomitant hypercalcemia of sarcoidosis and HPT are distinguishable by radiographic and laboratory analyses and by the Dent corticosteroid suppression test. Hypercalcemia of primary HPT is associated with elevated serum C-terminal parathormone, osteitis fibrosa, a negative Dent test, and a chloride/phosphate ratio greater than 33 in 94% of primary HPT patients. Hypercalcemia of sarcoidosis is associated with a normal or decreased C-terminal parathormone assay and a positive Dent test, as well as elevated serum immunoglobulins and erythrocyte sedimentation rate, and a positive angiotensin-converting enzyme assay.(ABSTRACT TRUNCATED AT 250 WORDS)