Functional large parathyroid carcinoma extending into the superior mediastinum.

Mediastinal parathyroid carcinoma is very rare regardless of whether it is functioning, and it is sometimes problematic in both diagnosis and treatment. We herein report a case of primary hyperparathyroidism (PHP) associated with large parathyroid carcinoma extending into the superior mediastinum successfully removed by a transcervical approach, with a review of recent literature. A 61-year-old male with a six-year history of PHP and urinary stone disease presented with an abnormal mediastinal mass in a chest X-ray. His serum level of intact parathyroid hormone (PTH) was markedly elevated to 1,220.0 pg/mL (normal range: 10.0-65.0 pg/mL), though calcium and phosphorus levels were within normal limits. Chest computed tomography demonstrated a large mass in the superior mediastinum, displacing the trachea to the right and reaching the aortic arch, posteriorly adjacent to the thoracic vertebra. Transcervical extirpation of the tumor was performed. The resected specimen measured 50x85x38 mm and weighed 56.8 g. Histopathological examination revealed a capsular invasion of the tumor cells, and a diagnosis of parathyroid carcinoma was made. On the 8th postoperative day, the patient was discharged uneventfully with a decreased serum level of PTH (59.0 pg/mL), and no recurrent disease or exacerbation of hyperthyroidism was observed 36 months after surgery.