Mr. S.J, 39 year old male, first presented to his general practitioner with 18 months history of globus sensation in his throat in conjunction with dysphagia for both solids and liquids. Physical examination was unremarkable apart from a large soft, well circumscribed subcutaneous painless mass on posterior upper left chest wall. Non-contrast CT chest demonstrated a fat containing lesion measuring 95 x 80 x 30mm suggestive of intramuscular lipoma. Incidentally, there was a 48 x 55 x 25mm well circumscribed nonenhancing soft tissue density in the superior anterior mediastinum without associated lymphadenopathy. PET-CT scan done 3 months after the initial CT scan showed stable size of the mediastinal mass with no FDG avidity. The patient underwent mini median sternotomy with excision of mediastinal mass and thymus. Histology revealed a normal thymus without evidence of lymphoma or thymoma. The entire mediastinal mass consisted of a 45 mm stage 1 T3N0M0 cystic papillary thyroid carcinoma with clear margins. In light of the histological findings, Mr. S.J underwent total thyroidectomy of orthotopic thyroid. Histology showed a benign thyroid tissue with one normal parathyroid gland within the left hemithyroid.
Majority of ectopic thyroids are discovered incidentally on imaging. Hounsfield units of ectopic thyroid tend to be lower than that of orthotopic thyroid. Most common anatomical location for an ectopic thyroid is within the Wölfler region. Lingual ectopic thyroid comprises 50-90% of the all ectopic thyroids. So far, fewer than 10 cases of mediastinal ectopic thyroid have been reported, with majority in the anterior mediastinum. Other intrathoracic locations of ectopic thyroid have been described in the right ventricle and lung parenchyma. Thyroid carcinoma in ectopic thyroids are rare, comprising of less than 1% of all lingual thyroids.