Primary intrathoracic goiter on scintigraphy

A 69-year-old woman with a history of goiter and thyrotoxicosis over the previous year was seen for radioiodine therapy. At the time of a previous ablation with I-131, a thyroid scan was performed after administration of Tc-99m sodium pertechnetate. Scintigraphy showed an enlarged thyroid gland with increased thyroid uptake in the neck at its normal location along with mediastinal uptake. Contrast enhanced computed tomography (CT) showed an anterior mediastinal mass. This mass was excised. Histologic study demonstrated an ectopic primary intrathoracic nodular goiter at the site of increased activity seen on Tc-99m pertechnetate imaging.