Ectopic parathyroid adenomas are estimated to occur in 4% to 20% of patients with primary hyperparathyroidism. Possible sites of ectopic parathyroid location include the parapharyngeal space at the level of the mandible, intrathyroidal, the carotid sheath and the mediastinum. Ectopic inferior parathyroid glands are commonly found in the anterior mediastinum in an intrathymic location but can rarely be extrathymic. Mediastinal parathyroid adenomas can also occur rarely in the middle mediastinum in the aortopulmonary window or the precarinal location.

Mediastinal parathyroid adenomas must be well localized prior to surgery in order to determine the best operative approach. Ideally, the lesion should be visualized/located on 2 different tests, which most commonly include sestamibi scanning. Most patients who undergo mediastinal exploration for parathyroid adenoma do so after failed neck exploration. However, due to the increasingly frequent use of sestamibi scanning in patients with primary hyperparathyroidism, patients who are found to have a medistinal parathyroid adenoma are now undergoing direct mediastinal exploration without neck exploration.

Video-endoscopic exploration of the mediastinum is most commonly performed via thoracoscopy. We describe the technique of resection of ectopic parathyroid adenoma in the AP window and in the thymus.