Abstract
Ectopic parathyroid adenomas can be encountered during four gland explorations, but nearly 80% of adenomas are localized with ultrasound and sestamibi imaging. Ectopic adenomas are thought to arise from abnormal migration during development. As a cervical congenital anomaly, common carotid artery agenesis is an extremely rare anomaly characterized by separate origins of the internal and external carotid arteries directly from the aortic arch. Here we present a case of a 75 year old man with primary hyperparathyroidism who was found to have congenital agenesis of the common carotid artery associated with an ectopic parathyroid adenoma within the parapharyngeal space, which mimicked a carotid body tumor based on location and imaging. The successful identification and resection of the ectopic parathyroid adenoma presented here demonstrate the importance of preoperative imaging studies to allow appropriate operative planning as well as the utility of intraoperative parathyroid hormone assay in predicting cure during surgery.
1
Introduction
The prevalence of ectopic parathyroid adenomas (PA) is low, found in various locations in 6–22% of patients with hyperparathyroidism (HPT) , while an ectopic gland within the carotid sheath remains rare. Additionally, common carotid artery agenesis is an extremely rare congenital anomaly characterized by separate origins of the internal and external carotid arteries directly from the aortic arch . Here we present a case of congenital agenesis of the common carotid artery associated with an ectopic PA within the parapharyngeal space, which mimicked a carotid body tumor. This report highlights the importance of preoperative imaging and the utility of intraoperative parathyroid hormone (PTH) measurement to positively identify an ectopic PA in the setting of aberrant carotid anatomy.
2
Case description
A 75 year-old gentleman with primary hyperparathyroidism (HPT) was seen during a hospitalization for extensive body surface burns. His past medical history was significant for hypertension, type 2 diabetes mellitus, hyperlipidemia and prostate cancer. He denied any history of nephrolithiasis, osteopenia or depression. Family history was unremarkable. Laboratory studies demonstrated a PTH value of 221 pg/mL and serum calcium of 12.2 mg/dL.
Physical exam was unremarkable except for bilateral lower extremity burn wounds. Initial 99m Tc-sestamibi scintigraphy revealed asymmetry in the left neck region but did not localize the parathyroid adenoma ( Fig. 1 ). A contrasted neck CT scan demonstrated a 4.0 × 2.5 × 1.0 cm lesion in the left parapharyngeal space ( Fig. 2 ) suspicious for a paraganglioma based on its location, with no parathyroid adenoma identified. On angiography the lesion was hypervascular and incidentally revealed left common carotid artery agenesis ( Fig. 3 ).
