Supernumerary Mediastinal Parathyroid Carcinoma Resulting in Recurrent Primary Hyperparathyroidism and Hypercalcemic Crisis: A Case Report

Supernumerary Mediastinal Parathyroid Carcinoma Resulting in Recurrent Primary Hyperparathyroidism and Hypercalcemic Crisis: A Case Report

Primary hyperparathyroidism is a common cause of hypercalcemia but is rarely caused by a parathyroid carcinoma. Supernumerary glands are also uncommon in the setting of recurrent disease. We present a case of an 87-year-old female who presented in a hypercalcemic crisis due to recurrent primary hyperparathyroidism. Imaging studies showed a large parathyroid adenoma in the superior mediastinum believed to be a supernumerary gland. She was taken for a joint operation with ear, nose and throat and thoracic surgery where she underwent a thoracoscopic resection of the gland. The lesion appeared to be locally invasive involving the mediastinal fat and azygous vein. Intraoperative parathyroid hormone (PTH) levels showed an appropriate drop and post-operative calcium levels normalised. Final pathology showed a 5 cm parathyroid adenoma which in the setting of her significantly elevated PTH and locally aggressive lesion would be consistent with a supernumerary parathyroid carcinoma.