RESUMO
INTRODUCTION: Parathyroid gland has a distinct physiologic and endocrinologic role in the body system. Primary hyperparathyroidism is the most common cause of hypercalcemia with a marked female dominance. It is characterized by hypercalcemia, hypophosphatemia and elevated parathyroid hormone. Parathyroid adenoma, parathyroid hyperplasia and parathyroid carcinoma form the differential diagnosis. Giant parathyroid adenomas are rarely symptomatic than non-giant parathyroid adenomas and parathyroid carcinoma. CASE PRESENTATION: A 41 years old previously healthy male patient with undetectable surgical and familial history presenting with left clavicle fracture by mild trauma. He was diagnosed for primary hyperparathyroidism after the finding of multiple bony lesions and elevated serum calcium and Parathyroid hormone. Preoperative imaging aided in diagnosis of a parathyroid lesion and secondary bone resorption lesions (brown tumors). After adequate medical treatment and preparation, selective right lower parathyroidectomy was held, and the final pathology came with a giant parathyroid adenoma. CONCLUSION: Primary hyperparathyroidism should be suspected when dealing with a hypercalcemic patient having osteolytic bony lesions. Distinguishing Parathyroid adenoma from carcinoma is a challenging and essential preoperative step in planning and surgical procedure.