Giant parathyroid adenoma causing primary hyperparathyroidism

Giant Parathyroid Adenoma (GPA) is a rare cause of primary hyperparathyroidism (PHPT) with unique clinical and operative implications. While symptoms of GPA are similar to that of enlarged parathyroids in the setting of PHPT, key differences exist. The tissue and receptor composition of GPAs differ from their parathyroid adenoma counterparts; hence their size does not always correlate with a commensurate elevation of parathyroid hormone (PTH). Further, the mass of GPA increases the rate of migration into the mediastinum and can apply pressure on vital structures, leading to more challenging resections and unique clinical presentations such as recurrent syncope. We report a case of a GPA with extension into the superior mediastinum, the surgical challenges associated with its resection and its pre- and post-operative implications on clinical symptoms and biochemical markers. The data shared in this report may contribute to the creation of a more comprehensive database on GPA and a better understanding of this distinct entity.