Recurrent parathyroid cystic disease.

Cystic masses of the neck may represent thyroid, parathyroid, thyroglossal duct or branchial cleft cysts. Analysis of the cyst fluid may establish the etiology. Elevated levels of parathyroid hormone can be found in parathyroid cysts without concomitant hyperparathyroidism. A high concentration of cholesterol without the finding of thyroglobulin or parathyroid hormone in the fluid aspirated from a lateral neck mass suggests a branchial cleft cyst.