We report a rare case of an intrathymic primary intrathoracic goiter. The patient with newly diagnosed breast carcinoma was also known to have a distinct large anterior mediastinal mass. This was removed via a median sternotomy, after a thorascopic biopsy had been performed in the past but a diagnosis had not been reached. A discussion relating to the extremely rare occurrence of intrathymic ectopic thyroid tissue and the surgical treatment of primary intrathoracic goiters is included.
