Functional and nonfunctional parathyroid carcinoma: two case reports and literature review

Parathyroid carcinoma (PC) is a rare malignant endocrine tumor. It can be divided into functional and non-functional types according to the tumor's ability to secrete parathyroid hormone. Herein, we present a case each of functional and nonfunctional PC. Case 1: Functional PC. The main clinical symptoms were high parathyroid hormone and hypercalcemia with bone injury and other complications. The mass was large, capsulated, and showed vascular invasion. The tumor was surgically removed, along with a part of the tracheal wall and recurrent laryngeal nerve that were invaded by the tumor. The ipsilateral and isthmus thyroid lobe and central lymph nodes were also removed. Medicines were given to lower blood calcium. The patient died 18 months after surgery because of severe pulmonary infection and tracheal stenosis. Case 2: Non-functional PC. The patient showed no obvious clinical symptoms, but physical examination revealed a thyroid nodule. Despite the small diameter, the mass still invaded the surrounding thyroid lobe, fat, and muscle tissue. Surgery was performed to remove the tumor and ipsilateral thyroid lobe and central lymph nodes. The patient survived without recurrence or metastasis. Thus, we believe that the prognosis of PC negatively correlates with the scope of surgery. Early surgery can improve patient prognosis, and physical examination is conducive to early detection of PC. Herein, we provide a description of the diagnostic workup and the treatment approach and review relevant studies. We summarize the clinicopathological characteristics of PC cases to provide evidence for early diagnosis and therapy, to improve patient prognosis.