Retropharyngeal Parathyroid Glands: Important Differences

Retropharyngeal Ectopic Parathyroid Adenoma Localized by 18F-Fluorocholine Positron Emission Tomography/Computed Tomography: A Case Report

Ectopic parathyroid adenomas of the retropharyngeal space are relatively rare. Herein, we report a case of primary hyperparathyroidism (PHPT) secondary to a retropharyngeal parathyroid adenoma. A 22-year-old woman presented with elevated serum calcium and parathyroid hormone (PTH) levels, revealed during a medical check-up. The patient had a history of ureteral stones and a confirmed low bone mass. Neck ^99mTechnetium-sestamibi singlephoton emission computed tomography (CT) and ultrasonography did not reveal any suspicious lesions. There was no evidence of hereditary PHPT based on the results of targeted gene sequencing. Surgical exploration was unsuccessful, and the PHPT persisted after the first surgery. Approximately a year after the failed operation, ¹⁸F-fluorocholine (FCH) positron emission tomography/CT (PET-CT) became available, and when performed, it revealed increased uptake in the retropharyngeal space of the right side of the neck. The results of parathyroid venous sampling were concordant with a >2-fold elevation of PTH level in the veins on the right side of the neck compared to the peripheral veins. The 1.8 cm-diameter mass was successfully removed resulting in an 87% reduction in intraoperative PTH level (198.0–26.5 pg/mL). Subsequently, normalizations of calcium and PTH levels were achieved. In summary, ectopic parathyroid adenomas, including retropharyngeal lesions, should also be suspected when investigating an elusive case of PHPT. ¹⁸F-FCH PET-CT can be a useful complementary modality for detecting culprit lesions.

Parathyroid Surgery: What Radiologists Need to Know

Surgical intervention remains the mainstay of treatment of hyperparathyroidism and provides the highest chance at cure. After the disease is confirmed by biochemical testing, surgeons must use a combination of patient clinical history and radiographic imaging to determine the most appropriate surgical strategy. Through either minimally invasive parathyroidectomy or bilateral cervical exploration, surgeons provide high rates of cure for hyperparathyroidism with low rates of persistence or recurrence.

A rare cause of persistent hyperparathyroidism

In a case of patient with persistent hypercalcemia after parathyroidectomy, different imaging techniques and particularly 18F-fluorocholine PET/CT are important to localize the adenoma even in a very unusual location.

Retropharyngeal ectopic parathyroid adenoma versus lymph node: Problem solving with CT neck angiogram

A 66-year-old female underwent preoperative evaluation for primary hyperparathyroidism. Ultrasound (US) neck and technetium (Tc)-99m-sestamibi planar scintigraphy were negative, but single photon emission computed tomography/computed tomography (SPECT/CT) demonstrated a tracer-avid retropharyngeal nodule compatible with parathyroid adenoma (PTA). A retrospective review of CT neck angiogram (CTA) and neck magnetic resonance imaging (MRI) performed 4 months earlier for stroke evaluation revealed arterial phase hyperenhancing retropharyngeal tissue, which had been dismissed as a nonpathological lymph node. “Polar vessel sign” seen in two-thirds of PTA was also present on retrospective review of the CTA. The concordant findings between SPECT/CT and CTA were indicative of a solitary undescended ectopic PTA in the retropharyngeal space, an uncommon location. A successful surgical cure was achieved after minimally invasive parathyroidectomy. This case highlights the retropharyngeal space as an important ectopic site of PTA, limitation of US, and Tc-99m-sestamibi planar scintigraphy in identifying retropharyngeal PTA. We also discuss the role of CT and MRI and the challenge in differentiating retropharyngeal PTA from a lymph node.