Parathyroid cysts.

Parathyroid cysts are a rare cause of primary hyperparathyroidism. A case is presented of a 25-year-old black man who presented with hyperparathyroidism and at operation was found to have a 2.5 cm parathyroid cyst at the left inferior position. The cyst contained clear fluid, and the wall was thickened and composed of hyperplastic parathyroid tissue. The remaining glands were smaller but also hyperplastic. Subtotal parathyroidectomy was performed. This case presents many of the typical features of parathyroid cysts. The pertinent literature is reviewed. Parathyroid cysts present as two distinct groups, functioning and nonfunctioning. The former are more common in men, and the cyst is more likely to be secondary to degenerative changes in a hyperplastic gland. In contrast, nonfunctioning parathyroid cysts are more common in women and present as neck masses or incidental findings at operation. The different proposed etiologies for parathyroid cysts are discussed. Preoperative diagnosis is rare but important as it may prevent an unnecessary neck exploration or thyroidectomy. The diagnosis should be suspected with any cystic neck mass that yields clear fluid on aspiration, especially if it is in the inferior position. The fluid should be submitted for parathormone evaluation. Aspiration alone has been curative in some cases.