This is a 53-year-old woman with PHPT. CT demonstrated an ectopic 1.3 × 0.9 cm parathyroid gland in the anterior mediastinum, just inferior to the innominate vein. The patient underwent robot-assisted thoracoscopic thymectomy. The PTH declined from 128 pg/mL at baseline to 42 pg/mL at the end of the case.CT, computed tomography; PHPT, primary hyperparathyroidism; PTH, parathyroid hormone.