Unexpected Appearance of Ectopic Mediastinal Toxic Nodulary Thyroid Hyperplasia in a Case of Recurrent Hyperthyroidism

Ectopic mediastinal thyroid is a rare entity. Patients are usually euthyroid and symptoms due to mediastinal compression are cautionary to investigate intratoracic mass. We represent a female patient who had undergone subtotal thyroidectomy 12 years ago and had recurrent hyperthyroidism following an euthyroid period. Antithyroid antibodies were negative. Thyroid ultrasonography showed residual thyroid tissue in both sides and multiple nodules on the right side. Thyroid scintigraphy showed a nonhomogenously increased tracer uptake on the right thyroid lobe and left lobe was rather suppressed. Additionally, a large mass of nonhomogenously increased activity located in the mediastinum which was totally seperate from the thyroid gland was detected. MRI images supported that the thoracic mass was an ectopic thyroid tissue and surgical excision confirmed benign nodulary hyperplasia.The case is intereseting in the way that the patient had a recurrent hyperthyroidism due to toxic nodular hyperplasia of the mediastinal ectopic thyroid gland and the pathology was first realised by Technetium-99m (Tc-99m) pertechnetate thyroid scan