Clear parathyroid cysts and hyperparathyroidism.

There is reason to believe that clear parathyroid cysts are a separate pathologic entity distinct from degenerative cystic tumors of the parathyroid. They probably derive from enlargement of vestigial tubules or canals associated with parathyroid embryogenesis and they are rarely, if ever, hyperfunctioning. Indeed, if a clear parathyroid cyst is encountered in the clinical setting of primary hyperparathyroidism, then it is important to exclude a concomitant tumor in one of the other parathyroid gland, as in the case presented here. If the ionized serum calcium level is normal then clear parathyroid cysts can be diagnosed and treated definitively by percutaneous needle aspiration of their crystal clear fluid contents.