Functional mediastinal parathyroid cyst: report of a case.

We report herein a rare case of a functional mediastinal parathyroid cyst. A mediastinal tumor was detected by a chest X-ray film and subsequent computed tomography (CT) scan in a 68-year-old woman who was asymptomatic. Biochemical examination revealed that her serum calcium and intact-parathyroid hormone (i-PTH) levels were above the normal range. The findings of chest CT and magnetic resonance imaging suggested a cystic mass. The mass, which adhered tightly to its surrounding structures, was resected through a median sternotomy. The patient had an uneventful postoperative course, and her serum calcium and i-PTH levels rapidly returned to within the normal range.