Functioning lipoadenoma of a supernumerary parathyroid gland in the mediastinum.

A patient underwent reexploration for a parathyroid adenoma; following identification of four normal glands in the cervical region, the mediastinum was entered, and an intrathymic lipoadenoma was excised. These very rare tumors have been associated with hypercalcemia in approximately half of the previously reported cases; however, none has previously been described as occurring entirely in the mediastinum.