Hyperparathyroidism: a rare mediastinal presentation of an ectopic adenoma

The aortopulmonary window is a rare location of an ectopic parathyroid gland, but one that must be considered in persistent primary hyperparathyroidism despite previously attempted parathyroidectomy. Multiple diagnostic studies, including nuclear scans and anatomical imaging techniques, are crucial for identification of a parathyroid gland in the mediastinum and prevention of unnecessary exploratory surgical intervention. This case report presents a 55-year-old female patient with persistent hyperparathyroidism following a neck exploration and thyroidectomy for a parathyroid adenoma. Serial sestamibi scans and CT imaging over the subsequent few years were suggestive, but not diagnostic, of a mediastinal adenoma. Four years after the initial surgery, however, imaging studies identified the development of a soft tissue mass with increased uptake in the aortopulmonary window. A median sternotomy was performed at that time. An ectopic parathyroid gland was identified during surgery between the aortic arch and the bifurcation of the pulmonary artery, as demonstrated on imaging and confirmed by frozen section. Two years following the sternotomy, the patient remains symptom free with calcium and parathyroid hormone (PTH) levels within reference ranges.