ABSTRACT
Brown tumor or Osteitis Fibrosa Cystica [OFC] is a rare clinical entity complicating hyperparathyroidism. It may occur in the head and neck, with the mandible being the most frequent site. Primary hyperparathyroidism is usually associated with hypercalcemia. We report a 35 years old female with mandibular brown tumor secondary to primary hyperparathyroidism. In this case in spite of primary hyperparathyroidism and the bony lesion the serum calcium level was within normal limit. This case demonstrates that in osteolytic bony lesions a hyperparathyroidism complication can be expected even with normal serum calcium level. The presence of normocalcemia in hyperparathyroidism should prompt the physician to measurement of ionized calcium and look for vitamin D deficiency, magnesium deficiency, impaired renal function, use of interacting drugs and associated disorders. If there weren't these factors, normocalcemic primary hyperparathyroidism should be considered