A Hyperthyroid Patient With Ectopic Mediastinal Thyroid Goiter Affected by Graves Disease:

True ectopic mediastinal thyroid goiters are rare developmental anomalies, accounting for less than 1% of all thyroid ectopies, whereas Graves disease in an ectopic mediastinal thyroid goiter has been reported only twice in the international literature. A 51-year-old female patient with poorly controlled hyperthyroidism, secondary to Graves disease was referred to our unit for thyroidectomy. A preoperative thyroid scan disclosed an ectopic thyroid goiter below the lower pole of the left thyroid lobe completely isolated from the cervical pretracheal thyroid gland. Intraoperatively, an ectopic mass, macroscopically compatible to thyroid tissue, attached to the posterior surface of the left upper horn of the thymus gland, was found. The patient underwent total thyroidectomy followed by resection of the ectopic goiter. Histologic examination confirmed the thyroid nature of the ectopic tissue, showing findings compatible with Graves disease, in both the thyroid gland and the ectopic tissue. There were also loci of papillary carcinoma in the cervical thyroid gland. When a pretracheal thyroidectomy for symptomatic thyroid disease is planned, preoperative thyroid scan should be performed to detect possible ectopic thyroid tissue. The English literature reports that untreated ectopic mediastinal thyroid tissue can lead to failure to cure the hyperthyroidism in Graves disease or leave untreated coexisting malignancy in the ectopic tissue.