A 7.3×5.3×3.5-cm heterotopic thyroid in the posterior mediastinum in a patient with situs inversus totalis

Ectopic posterior mediastinal thyroid is a very rare clinical disease entity. It accounts for less than 1% of all mediastinal tumors. The mass is difficult to diagnose due to its rarity and non-specific clinical symptoms and thus remains asymptomatic for many years until it becomes larger. Since the mass is considerably large at presentation, it should be distinguished from metastatic thyroid carcinoma. We present herein the case of a 62-year-old woman with situs inversus totalis who complained of atypical chest pain and dysphagia and had a huge posterior mediastinal ectopic thyroid. The patient underwent complete resection through thoracotomy, with relief of symptoms. In summary, although ectopic posterior mediastinal thyroid is a rare disease entity, it should be considered in the differential diagnosis of posterior mediastinal tumors. Surgery is the treatment of choice for posterior ectopic posterior thyroid and its prognosis is excellent following complete resection.