Primary hyperparathyroidism due to a giant parathyroid adenoma presenting with pathological fractures and multiple brown tumors.

Summary: Primary hyperparathyroidism (PHPT) is a disorder in which excessive parathyroid hormone (PTH) is secreted from the parathyroid glands. The cause of PHPT is most commonly parathyroid lesions such as parathyroid adenoma. The clinical manifestations of PHPT include hypercalcemia, nephrolithiasis, bone disease and rarely pathological fractures and brown tumors, which arise within the foci of osteitis fibrosa. Brown tumors are benign intraosseous tumors that occur because of excessive osteoclast activity. Because of advances in medical care, early diagnosis and treatment have meant that diagnosing PHPT in the setting of multiple brown tumors is particularly rare. Here, we present a case of a young man with prolonged PHPT from a giant parathyroid adenoma with multiple brown tumors causing pathological fractures. Definitive treatment of PHPT is parathyroidectomy with particular attention to the risks for hungry bone syndrome (HBS) postoperatively. Learning points: Pathological fractures from brown tumors are a rare but significant concern in prolonged PHPT, and a multidisciplinary approach is required including orthopedic surgery, otolaryngology and endocrinology.It is important to assess PTH and calcium in the context of hypercalcemia with bone lesions to avoid potential diagnostic delays.Postoperative parathyroidectomy patients with large parathyroid adenomas, elevated alkaline phosphatase, elevated PTH and the presence of brown tumors are at particularly high risk for HBS.Very high levels of PTH, calcium, alkaline phosphatase and multiple brown tumors should raise concern for a potential case of parathyroid carcinoma.Indications for genetic testing for inheritable parathyroid disease include patients younger than 30 years old, those with multigland disease, those with a family history of hypercalcemia or syndromic disease and those with atypical parathyroid adenoma and parathyroid carcinoma.