Carcinoma in a Mediastinal Fifth Parathyroid Gland

Abstract

COMMONLY four parathyroid glands are located in the neck.^1,2The incidence of a fifth supernumery parathyroid gland has been reported to be between 2% and 6%.^1,2Most reports of a hyperfunctioning supernumery parathyroid gland have been adenomas.^3-5There have been only a few reports of parathyroid gland carcinoma occurring outside of the cervical region,^6-9none of which were in a supernumery parathyroid gland. We believe this is the first report of a carcinoma occurring in a supernumery parathyroid gland. The patient is free of recurrence seven years after surgical excision. <h3>Report of a Case</h3> A 57-year-old woman was seen in the emergency department with a sprained ankle. Roentgenograms of the ankle revealed no evidence of skeletal trauma, but because of marked osteopenia, testing for serum calcium levels was performed, with values of greater than 15 mg/dL (&gt;3.74 mmol/L). The patient's detailed history was normal, aside from