Abstract 112: A case of primary hyperparathyroidism presenting as giant cell tumor

Introduction: Primary hyperparathyroidism is a metabolic bone disease characterized by hypercalcemia, hypophosphatemia, and inappropriately elevated PTH due to autonomous production of parathormone by a parathyroid adenoma, hyperplasia or rarely, carcinoma. We report a case of primary hyperparathyroidism presenting as giant cell tumor. Clinical Case: A 33-year-old male presented with swelling ofmandible for the last 1 year for which he was operated. Histopathology revealed giant cell tumor. After resection of mandibular swelling, he developed pain and swelling in left ankle for the last 2 months. On evaluation, he was found to have an expansile lyticlesionin the lower half of tibia and fibula. He underwent bone curettage and Histopathology revealed giant cell tumor. Skeletal survey was done later which showed multiple lytic lesions, and he was referred to endocrinology. On evaluation, he was found to have corrected serum calcium 15.46 mg/dl, phosphate 2.57 mg/dl, alkaline phosphatase (ALP) 2831 IU/ml, iPTH 645.5 pg/ml, 25(OH)D 11.18 ng/ml, and serum creatinine 0.9 mg/dl. His serum prolactin was 6.74 ng/ml. Ultrasonography (USG) of abdomen revealed normal study. CECT Abdomen revealed tiny 1-2 mm calculi in Bilateral kidneys. He did not have gallstone disease or pancreatitis. USG of neck and 99m Tc-sestamibi scan localized right inferior parathyroid adenoma. Based on above findings a diagnosis of primary hyperparathyroidism due to parathyroid adenoma was made. Discussion: Brown tumor is a manifestation of hyperparathyroidism and is not a tumor. They are usually multiple and present in long as well as in flat bones. However, osteoclastoma (giant cell tumor) is a neoplasm of bone and manifest as a solitary lytic lesion in long bone. Brown tumor and osteoclastoma are indistinguishable on imaging and histology; however, calcium profile can differentiate between the two disorders.