Abstract
A 36-year-old man who had schizophrenia developed hypercalcemia and hyper-alkaline-phosphatasemia. He was diagnosed as having hyperparathyroidism, due to the presence of a high serum intact-PTH level (1221 pg/ml). A soft mass (4 cm in diameter) was palpable in the right side of the neck. On US and CT, the mass was found to be a cystic tumor located in the right lobe of the thyroid. MIBI scintigraphy revealed a hot spot in the same area of the right lobe. A diagnosis of intrathyroidal parathyroid cyst was made, and a right hemi-thyroidectomy was performed. The intact-PTH level in the cyst fluid was 317,400 pg/ml. Immediately after surgery, the serum intact-PTH level decreased. Hypocalcaemia was observed on the third post-operative day. On histopathology, the wall of the cyst was found to consist of a chief cell adenoma. A functional parathyroid cyst is rare, and an intrathyroidal functional parathyroid cyst is even rarer. This report presents the case and reviews the relevant literature.
