PARATHYROID CARCINOMA: ULTRASONOGRAPHIC AND CLINICAL EXPERIENCE.

Parathyroid cancer is an extremely rare malignancy that usually leads to hyperparathyroidism. The aim of this report is to present clinical and ultrasonographic features of tumors in six patients (5 females; mean age 53.2 years) treated for parathyroid carcinoma at the Department of Nuclear Medicine during 20 years. Most patients presented with hypercalcemia, and one of them had a previous history of long-term secondary hyperparathyroidism and was treated with hemodialysis. All patients had significantly reduced bone density, and two of them presented with typical 'brown' tumors involving long bones of lower extremities. After initial treatment, all patients except for the youngest female patient were in long-term remission with normal serum calcium and parathyroid hormone levels. Preoperative imaging procedures such as ultrasound with targeted fine needle-aspiration biopsy and Tc99m-sestamibi scan helped determine the location and extent of the disease, but definitive diagnosis was made after the surgery. Parathyroid cancer is a rare form of malignant tumor that is difficult to diagnose preoperatively due to similar clinical features with benign causes of hyperparathyroidism such as hyperplasia and adenomas, especially atypical ones that require regular follow-up. Complete surgical resection provides the best chance of cure, although metastatic disease is possible.