# Case Report: An undescended intravagal parathyroid adenoma: a rare cause of refractory primary hyperparathyroidism and severe osteoporosis

## TL;DR

A rare case of an undescended intravagal parathyroid adenoma causing severe hyperparathyroidism and osteoporosis is reported.

## Contribution

This case adds to the limited literature on intravagal parathyroid adenomas and highlights diagnostic challenges.

## Key findings

- A patient with persistent hypercalcemia and osteoporosis had an undescended intravagal parathyroid adenoma.
- Multimodal imaging identified the ectopic adenoma, confirmed intraoperatively.
- This case underscores the rarity and diagnostic difficulty of intravagal parathyroid adenomas.

## Abstract

Ectopic intravagal parathyroid adenomas represent an exceedingly rare clinical entity. Embryologically, parathyroid glands develop from the third and fourth pharyngeal pouches, migrating to their definitive locations on the inferior and superior aspects of the thyroid. While ectopic locations are well described, intravagal variants are rare, with few documented cases in the literature. We report an additional unique case of a patient with persistent hypercalcemia and severe osteoporosis following a failed bilateral neck exploration for primary hyperparathyroidism. Following multimodal structural and functional radiological evaluation, an ectopically undescended parathyroid adenoma was identified and subsequently confirmed intraoperatively to be situated intravagal.