Incidental Findings with Technetium-99m Methoxyisobutrlisonitrile Imaging of Ectopic Parathyroid Hyperplasia in Patient with Intrathyroidal Parathyroid Hyperplasia

We report a case of intrathyroidal and ectopic parathyroid hyperplasia in a 47-year-old female patient with secondary hyperparathyroidism. During evaluation for end stage renal disease, hypercalcemia and hyperparathyroidism were detected in laboratory exam and thyroid nodules were found in computed tomography, and thyroid ultrasonography. In subsequent dual-phase technetium-99m methoxyisobutrlisonitrile (Tc-99m MIBI) scan, delayed focal uptakes were found in thyroid gland and the upper mediastinum. I-123 scan showed photon defects in thyroid gland and no uptake in the upper mediastinum. The imaging findings indicate intrathyroidal and mediastinal ectopic parathyroid hyperplasia. The intrathyroidal and ectopic parathyroid hyperplasia were confirmed by surgical approach. Tc-99m MIBI scan was useful for detecting ectopic parathyroid hyperplasia concomitant intrathyroidal parathyroid lesion.