A case report of rare giant parathyroid adenoma

Parathyroid adenoma weighing more than 3.5 g are referred as Giant parathyroid adenoma (GPA). These mainly present with primary hyperparathyroidism but have severe clinical presentations like severe hypercalcemia and significantly higher PTH levels. These features are sometimes indistinguishable from parathyroid carcinoma. We describe an interesting case and clinical course of a young woman with GPA. A 27 years old woman previously asymptomatic presented with pain in left leg along with difficulty in walking and was subsequently diagnosed to have fracture of neck of left femur and severe hypercalcemia. On evaluation, the patient was found to have PTH dependent hypercalcemia and severe osteoporosis. USG neck revealed well defined heterogenous hypoechoic lesion suggestive of parathyroid adenoma. Tc99 sestamibi scan showed tracer localization to inferior aspect of lower lobe of right thyroid gland. She underwent right inferior parathyroidectomy and a giant parathyroid adenoma (GPA) weighing 20 g was excised. Histology confirmed parathyroid adenoma with mainly chief type cells. The tumour excision resulted in significant decline in PTH levels. She developed severe hungry bone syndrome (HBS) in post operative period. She was treated aggressively for HBS with intravenous calcium gluconate, oral calcium supplements along with calcitriol. GPA present as distinct clinical entity with features different from both parathyroid adenoma and parathyroid carcinoma. We will highlight the distinguishing points of GPA from parathyroid adenoma and parathyroid carcinoma.