Undescended parathyroid adenomas as cause of persistent hyperparathyroidism

Undescended parathyroid adenomas (UPA) are very uncommon cause of primary and secondary hyperparathyroidism (HPT). They are far more represented in series of parathyroid reoperations for recurrent or persistent HPT after a failed initial cervical exploration. If an inferior gland has not been identified at the initial operation in an orthotopic or low thymic location, an undescended parathyroid gland should be suspected