Parathyroid cyst: report of case in the mediastinum.

Though a rare lesion a parathyroid cyst is of clinical significance because it usually mimics a thyroid cyst and can be associated with hyperparathyroidism. The cyst can be ectopic with location in the lateral neck or in the mediastinum and therefore constitutes a differential diagnosis to a branchial or thymic cyst. A case report of a mediastinal parathyroid cyst without hyperparathyroidism is presented. Fine needle aspiration with parathyroid hormone assay on the cyst fluid will reveal the correct diagnosis. Surgical removal of the cyst is recommended, and hyperparathyroidism should be considered.