Severe Hyperparathyroidism with Secondary Osteitis Fibrosa Cystica and Brown Tumors Mimicking Bone Metastasis

Introduction: The classical presentation of primary hyperparathyroidism, osteitis fibrosa cystica, has become very rare nowadays. This rarity makes it sometimes misdiagnosed leading to disastrous outcomes. Methods: We present a case of an undiagnosed primary hyperparathyroidism with severe osteitis fibrosa cystica and brown tumors that was first misdiagnosed as having bone metastasis. Conclusion: Osteitis fibrosa cystica although rare should be considered in the differential diagnosis of patients presenting with multiple brown tumors, especially since the diagnosis can be easily made by a simple calcium level, thereby avoiding severe adverse outcomes.