Autonomous thyroid adenoma, papilary thyroid carcinoma, and ectopic parathyroid adenoma in a patient with primary hyperparathyroidism and a nontoxic multinodular goiter

Dual radionuclide parathyroid scintigraphy with Tc-99m pertechnetate and TI-201 was performed before surgery in a 52-year-old woman with primary hyperparathyroidism and a nontoxic multinodular goiter. The study did not locate a parathyroid adenoma, but it detected an autonomous thyroid adenoma. A parathyroid exploration and a total thyroidectomy did not cure the hyperparathyroidism. Two occult papillary thyroid carcinomas were removed. Subsequently, Tc-99m sestamibi, CT, and MRI visualized an ectopic parathyroid adenoma overlying the ascending aorta missed with TI-201. This case shows the superiority of Tc-99m sestamibi to TI-201 in localizing an ectopic parathyroid adenoma and exemplifies the pitfalls in dual radionuclide subtraction parathyroid scintigraphy caused by coexisting benign or malignant thyroid disease