Primary Hyperparathyroidism: A Common Condition With an Uncommon Location.

Primary hyperparathyroidism (PHPT) is a prevalent clinical condition characterized by an inappropriate secretion of parathyroid hormone (PTH). It is most often caused by one or more parathyroid adenomas, which can, in rare cases, be ectopically located. Ectopic adenomas can pose a diagnostic challenge, lead to treatment delay, and be a common cause of recurrent hypercalcemia after parathyroidectomy. We present the case of a 73-year-old woman referred to our Endocrinology Department for hypercalcemia, with initial blood tests confirming primary hyperparathyroidism. Following a negative cervical ultrasound, a parathyroid sestamibi scan was performed, which identified an MIBI (technetium (Tc)-99m methoxyisobutylisonitrile)-avid focus in the midline posterior cervical region suggestive of an ectopic parathyroid adenoma. Subsequently, a four-dimensional neck CT scan revealed a retro-esophageal nodular lesion. The diagnosis was confirmed through esophageal endoscopic ultrasound-guided fine needle aspiration. The patient underwent minimally invasive parathyroidectomy with a significant intraoperative decrease in PTH levels and a postoperative normalization of calcium levels. Six months after surgery the patient shows no signs of recurrence. This clinical case highlights the importance of a thorough diagnostic workup and the use of multiple imaging modalities to accurately locate parathyroid adenomas. This approach helps prevent incorrect surgical procedures and improves treatment outcomes.