Hyperparathyroidism due to primary cystic parathyroid adenoma.

Three cases of parathyroid cyst are reported, bringing the total of reported functional and nonfunctional parathyroid cysts to 157 cases. Based on our findings a cystic parathyroid adenoma should be defined as a macroscopic cyst with a diameter larger than 1 cm. The three reported cases of functional parathyroid cysts suggest that they are not as rare as reported. Parathyroid cyst should be considered in every patient with a palpable neck mass, certainly in patients with hyperparathyroidism and a fluid-filled lesion at sonography. Functional parathyroid cysts may be multiple, therefore all four parathyroid glands should be identified, as during exploration for hyperparathyroidism. Our three cases show a preference for the inferior site which is in agreement with the literature. Nonfunctional, generally solitary, parathyroid cysts can be cured by percutaneous aspiration.