A case report of successful identification of ectopic parathyroid adenomas with a sequence of selective parathyroid venous sampling and 4D-computed tomography in a patient with recurrent hyperparathyroidism

INTRODUCTION: Recurrent hyperparathyroidism is difficult to manage due to the difficulty in finding the missing adenoma. Herein we present a case of recurrent hyperparathyroidism from ectopic adenomas which basic investigations failed to locate but were finally localized by a 4DCT following selective venous sampling (SVS) of parathyroid hormone (PTH). PRESENTATION OF CASE: A young female presented with recurrent hyperparathyroidism. She had severe primary hyperparathyroidism and temporary normocalcemia after first parathyroidectomy. Her hypercalcemia recurred and required second operation. However, the second operation was unsuccessful due to the pre-operation ultrasound, computed tomography (CT) neck, and sestamibi failed to identify the culprit parathyroid adenoma. After the second operation, positron emission tomography (PET), CT neck and sestamibi failed to identify the tumor but a sequence of SVS PTH and four-dimensional computed tomography (4DCT) successfully identified several ectopic adenomas. DISCUSSION: Ectopic parathyroid tissue is the most common cause of recurrent hyperparathyroidism but precisely locating these ectopic glands is often challenging. Despite modern modalities such as PET scans, the success rate is not impressive. SVS PTH is a good method to regionalize the ectopic source of PTH. With the more specified area, fine-tuning imaging with a 4DCT can identify the specific location of the ectopic parathyroid tissue. CONCLUSION: A sequence of SVS PTH followed by 4DCT could identify the exact location of ectopic parathyroid adenomas in a patient when conventional non-invasive imaging studies failed.