In this episode, Thoracic Surgeon Dr. Simon Turner discusses Mediastinal Masses. Imagine that you’ve ordered a chest x-ray on a patient of yours with shortness of breath. When you look at the x-ray the lungs look normal, but you notice to your surprise that the mediastinum looks quite abnormal. You speak with a radiologist who confirms your suspicions that your patient has a widened mediastinum and a probable mediastinal mass. What is the differential diagnosis of this x-ray finding and what should be done about it? Because mediastinal masses are not infrequently found incidentally on chest x-rays, every physician should have some basic knowledge about these lesions. The objectives include the: Anatomy of the mediastinum Differential diagnosis of mediastinal masses Approach to work-up and treatment of these legions