The mediastinum is a non-delineated group of structures in the thorax (chest), surrounded by loose connective tissue. It is the central compartment of the thoracic cavity. The mediastinum lies between the right and left pleura in and near the median sagittal plane of the chest. It extends from the sternum in front to the vertebral column behind, and contains all the thoracic viscera except the lungs. On the basis of cross-sectional imaging, mediastinum can be divided into 3 groups: 1) Prevascular compartment: which contains thymus, fat, lymph nodes and left brachiocephalic vein. 2) Visceral compartment, which contains trachea, carina, esophagus, lymph nodes, heart, ascending thoracic aorta, aortic arch, descending thoracic aorta, superior vena cava, intrapericardial pulmonary arteries, and thoracic duct. and 3) Paravertebral compartment: which contains the thoracic spine and paravertebral tissue. A wide variety of diseases involving these organs can present as a<unk>  or widening of the mediastinum on imaging studies. Mediastinal widening is diagnosed by the mediastinum measuring greater than 8 cm in width on PA chest x-ray. The<unk>  may present with symptoms or even without any symptoms. A<unk>  may cause a variety of symptoms by the mass pressing against other mediastinal structures, collectively known as mediastinal syndrome.<unk>  can be differentiated according to the content of the mass such as cystic mass, fatty mass or solid (tumor). Depending on location and composition of the mass further diagnosis is made by specific imaging studies, endoscopic studies, tissue biopsies, histopathological studies and/or growth of microorganism on specific culture medium.
Mediastinal mass
Diaphragmatic eventration
Pulmonary mass
Tracheal deviation
Lung mass
Mediastinal lipomatosis
Mediastinal hematoma
Mediastinal tumor