[A case of mediastinal parathyroid adenoma diagnosed by transtracheal needle aspiration].

Chest radiography of a 73-year-old man with upper abdominal pain showed hypercalcemia and an upper mediastinal mass. Functional mediastinal parathyroid adenoma was diagnosed, because of abnormally high levels of PTH in his serum and in fluid collected by transtracheal needle aspiration from the mediastinal mass. We resected the adenoma operatively. It a cystic tumor located behind the superior vena cava and the trachea. The inferior end of the tumor was as low as the aortic arch, and superiorly the tumor was attached to the inferior pole of the thyroid gland by a vascular pedicle. Histologically adenoma cells were predominant. This tumor was a mediastinal parathyroid adenoma by location, but because it was attached to the thyroid gland superiorly, it may have originated from the superior parathyroid gland and then descended because of its weight into the posterior superior mediastinum. Thus, it cannot be considered an ectopic parathyroid adenoma in origin. Mediastinal parathyroid adenoma is a rare disease, and these tumors are usually so small that correct localization of the adenoma is often difficult even by CT scan or scintigram. This is the first reported case of a mediastinal parathyroid adenoma that appeared as a mediastinal mass on a plain chest radiography and in which the level of PTH in the fluid collected from the mass by transtracheal needle aspiration was high.