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Retropharyngeal parathyroid adenoma: precise preoperative localization with CT and arterial infusion of contrast material.

E ctopic parathyroid glands tend to be located in positions defined by their embryologic path during fetal development FI ]. These locations are well known, and in a patient with hyperparathyroidism whose abnormal gland was not identified during surgery, the radiologist may be guided by this knowledge during subsequent attempts to locate the gland [2]. Rarely, an ectopic parathyroid gland may follow a variant embryologic path to an unusual location. We report an example of a parathyroid adenoma in an Uncommon location: the wall of the left pharynx at the level of the thyroid cartilage. The parathyroid adenoma was located using CT with arterial infusion of contrast material. Previous attempts to locate it using conventional dynamic CT, MR imaging, sonography, and planar and single-photon emission computed tomography (SPECT) sestamibi scintigraphy proved inadequate. Case Report A 67-year-old woman was referred for parathyroid identification after two surgical procedures for hyperparathyroidism. Initial preoperative sestamibi scintigraphy revealed increased radiotracer uptake in the regions of the right thyroid lobe and the left submandibular gland. During the first surgery, no abnormal parathyroid gland was identified and a partial thyroidectomy of the right thyroid lobe was performed. The patient remained hypercalcemic after surgery. A second sestamibi study showed persistent activity in the region of the left submandibular gland. During a second operation, the left submandibular gland and surrounding soft tissue were resected. Histologic evaluation revealed no parathyroid tissue and the patient’s hypercalcemia persisted. A third sestamibi scan, using planar and SPECT imaging, again showed abnormal uptake in the left neck (Fig. 1A). CT and MR imaging of the neck and chest were performed at another institution and considered nondiagnostic. Sonography of the neck showed only postsurgical changes. An arteriogram of the right common carotid revealed an ovoid hypervascular mass