Hyperfunctioning intrathyroidal parathyroid carcinoma

Intrathyroidal parathyroid carcinoma is an exceedingly rare cause of primary hyperparathyroidism with difficulties in the diagnosis and management. We report a case of hypercalcemia from intrathyroidal parathyroid carcinoma in a 63-year-old Saudi female. She was diagnosed 2 years earlier with osteoporosis in a primary care clinic and was on alendronate since then. This year she was noted to have hypercalcemia, but in retrospect she had more than 10 years history of multiple medical problems related to hypercalcemia. Parathyroid 99mTc-SestaMIBI scintigraphy revealed parathyroid adenoma in the left inferior parathyroid gland. She had successful video-assisted parathyroidectomy that relieved most of her symptoms. The extreme rarity of such a case, the interesting clinical presentation and review of the literature are discussed.