Mediastinal aberrant goiter characterized by high radiodensity on non-enhanced computed tomography: a case report

A mediastinal aberrant goiter is extremely rare, characterized by independence from the thyroid gland. This tumor most commonly develops in the anterior mediastinum and should be differentiated from a thymoma. Moreover, as mediastinal aberrant goiters frequently have a blood supply arising from the thoracic great vessels, preoperative diagnosis and evaluation of the feeding vessel are vital for safe surgery. Herein, we report a rare case of mediastinal aberrant goiter characterized by high radiodensity on non-enhanced computed tomography (CT).

A 77-year-old woman underwent non-enhanced CT, which showed a 2.2-cm, well-circumscribed, homogeneous anterior mediastinal nodule with high radiodensity. The CT attenuation value of the nodule was as high as 91.9 Hounsfield units. A thymoma or mediastinal goiter was suspected owing to the tumor location and the lack of a cystic component. We performed anterior mediastinal tumor resection using video-assisted thoracoscopic surgery. Pathologically, variably sized follicles, indicative of thyroid tissue, were observed with hemorrhage and hemosiderin deposition. Moreover, papillary projections of small follicles (Sanderson's polsters) were scattered without atypia of the follicular epithelium, indicative of an adenomatous goiter. The diagnosis of a mediastinal aberrant goiter was supported by the absence of an anatomical connection with the thyroid gland. The postoperative course was uneventful, and the patient was discharged on postoperative day 5.

The thyroid gland has a high radiodensity on non-enhanced CT, which correlates with iodine concentration. This radiological feature may be useful for the preoperative differentiation of mediastinal aberrant goiters containing thyroid tissue.