Persistent primary hyperparathyroidism is commonly caused by an ectopic parathyroid adenoma. The incidence of ectopic parathyroid tissue at carotid bifurcation is rare. Knowledge of embryogenesis is essential in localising and resecting these lesions.

A 31-year-old gentleman with persistent primary hyperparathyroidism following previous negative bilateral neck exploration (BNE) and sestamibi scan was referred to a tertiary specialist head and neck unit. He was found to have an ectopic parathyroid gland adjacent to the right internal carotid artery after specialist localisation studies with four-dimensional computed tomography (CT), and head and neck multidisciplinary discussion. Surgical exploration of the neck revealed a fusiform swelling adherent to the vagus nerve juxtaposing the right internal carotid artery. The lesion was excised and histology confirmed a 9-mm parathyroid adenoma. The patient recovered uneventfully with normalisation of serum calcium and parathyroid hormone (PTH), with no complications.

This case highlights the importance of understanding the embryogenesis and thereby potential ectopic locations of parathyroid glands. It also reflects the clinical importance of dedicated specialist head and neck unit comprising of radiologists, surgeons and pathologists in managing rare ectopic parathyroid adenomata following previous surgical exploration alongside negative sestamibi scintigraphy.