Mediastinal teratomas are rare extragonadal germ cell tumors. The majority are asymptomatic, but in one series of 66 patients ¹, 70% of patients presented with symptoms, predominantly chest pain, dyspnea and cough.

The case demonstrates a good example of the hilum overlay sign, described by Benjamin Felson, which states that a mediastinal mass anterior or posterior to the hilum will often extend laterally for a considerable distance and result in preserved visualization of the hilar vessels which can often be tracked medially to their confluence ². Computed tomography (CT) with intravenous contrast is the most important radiologic tool for evaluation since it depicts different tissue attenuations ³. A teratoma will typically be cystic and contain varying amounts of fat, soft tissue and calcification as in this particular case.