Multiple pathological fractures and muscle atrophy caused by a parathyroid carcinoma with postoperative hungry bone syndrome: A case report.

Background: Parathyroid carcinoma (PC) is a rare endocrine malignancy causing pathological changes such as abnormal bone metabolism, elevated serum calcium, and impaired renal function, and uncontrollable hypercalcemia is the main cause of death in PC patients. The diagnosis of PC is challenging and relying on postoperative histopathology. Radical surgery at the first time is the only effective therapy to cure PC. Hungry bone syndrome (HBS) is a relatively uncommon complication of parathyroidectomy characterized by profound and prolonged hypocalcemia, timely electrolyte monitoring and alternative interventional protocols can prevent symptomatic hypocalcemia.

Case: A 57-year-old man presented with multiple pathological fractures and muscle atrophy as the main symptoms accompanied by bone pain, hypercalcemia, elevated parathyroid hormone (PTH), and an enlarged left-sided neck mass. After consultation of multidisciplinary team, he was treated conservatively with plaster bandage fixation and infusion of intravenous zoledronic acid; and then complete resection of parathyroid mass + removal of involved tissue structures + left thyroid and isthmus lobectomy + lymph node dissection in the VI region in left neck were performed. The postoperative histopathology suggested a diagnosis of parathyroid carcinoma. Calcium and fluid supplementation and oral levothyroxine tablets were given postoperatively. Unexpectedly, the patient's PTH level decreased rapidly at 24 h postoperative, and serum calcium and phosphorus decreased continuously, and he felt numb around perioral sites and fingertips, which considered to be postoperative HBS complicated by parathyroidectomy. Then, a large amount of calcium supplementation and vitamin D were given timely and the patient got better at 1 month postoperatively. At 9-month postoperative, his bone pain and fatigue were significantly relieved compared with before with calcium, phosphorus, and PTH levels at normal range.

Conclusion: The possibility of parathyroid disease, particularly PC, should be considered in the presence of multiple pathological fractures, muscle atrophy, generalized bone pain, hypercalcemia, and clear neck mass. Radical resection of the tumor lesions at the first surgery is a key element affecting the prognosis of PC, and the effective management of preoperative hypercalcemia and postoperative HBS is also of great significance for improving prognosis.