Parathyroid adenoma associated with a branchial cleft cyst.

An unusual case of parathyroid adenoma is presented. This adenoma presented as a rapidly expanding neck mass in a normocalcemic patient. It was located far laterally in the neck, in association with the internal jugular vein and with a branchial cleft cyst. This case provides an unusual presentation of parathyroid adenoma. It also provides an elegant demonstration of developmental anatomy as well as the mechanism of parathyroid ectopia in the lateral aspect of the neck.