Ectopic parathyroid adenoma posterior to the trachea in the superior mediastinum causing refractory primary hyperparathyroidism: a case report.

Primary hyperparathyroidism (PHPT) caused by ectopic parathyroid adenomas in the superior mediastinum is rare and often leads to surgical failure. We report a case of severe PHPT in a 50-year-old female presenting with lower limb weakness and bone pain. Laboratory tests revealed marked hypercalcemia (serum calcium 3.48 mmol/L) and extremely elevated parathyroid hormone (PTH) levels (1920 pg/mL). Preoperative imaging, including neck ultrasound and 99mTc-MIBI SPECT/CT, precisely localized the ectopic adenoma to the superior mediastinum at the T1 vertebral level, posterior to the trachea, rather than in conventional parathyroid regions. The patient underwent successful complete resection of the tumor via meticulous neck and superior mediastinal exploration. Postoperatively, PTH and serum calcium levels normalized rapidly. In patients with biochemically confirmed PHPT and negative imaging in classical locations, the value of accurate preoperative imaging is underscored by this case as is intraoperative imaging guided exploration.