[Two cases of hyperfunctioning parathyroid cyst].

Two cases of parathyroid cyst were experienced. Both cases presented clinical data and symptoms of hyperparathyroidism. Microscopically, one had a thin fibrous wall containing parathyroid adenomatous tissue in the inner surface and the other showed cyst formation without any histological evidence of adenoma or hyperplasia. Most parathyroid cysts are non-functioning. In occasional cases, the cyst may contain a hyperfunctioning adenoma. The hyperfunctioning parathyroid cysts with normal parathyroid tissue are discussed.