Appearance of Ectopic Undescended Inferior Parathyroid Adenomas on Technetium Tc 99m Sestamibi Scintigraphy: A Lesson From Reoperative Parathyroidectomy

Hypothesis: Critical postoperative review of technetium Tc 99m sestamibi scintigraphy can identify an undescended parathyroid adenoma on scans initially interpreted as nondiagnostic or negative. Design: Case series. Setting: A single, tertiary care academic medical center. Patients: Three patients with persistent hyperparathyroidism. Intervention: Technetium Tc 99m sestamibi scanning. Outcome Measure: Medical records, operative reports, selective venous sampling results, and sestamibi scans were reviewed to identify scintigraphic findings diagnostic of an undescended parathyroid adenoma. Results: All patients were cured of their persistent or recurrent hyperparathyroidism during reoperation by resection of an undescended inferior parathyroid adenoma. Subsequent review of the preoperative sestamibi scans demonstrated scintigraphic evidence of the undescended adenoma. In each case there was asymmetry in the physiologic activity attributed to the ipsilateral submandibular gland that, in fact, corresponded to an ectopic parathyroid adenoma at the level of the carotid bifurcation. Conclusions: Careful attention to the contour of radioactivity in the region of the submandibular salivary gland may alert surgeons to the presence of an undescended inferior adenoma. After corroboration, this finding may facilitate a targeted operation.