Miscellaneous Lesions of the Mediastinum

A group of several miscellaneous lesions may arise within one or more of the mediastinal compartments that are distinct from benign or malignant neoplasms, cysts, lymphadenopathy, and vascular lesions. Such entities cannot be classified as one specific disease type, and include extramedullary hematopoiesis and multiple types of herniations, specifically hiatal, paraesophageal and Morgagni hernias. Extramedullary hematopoiesis typically manifests as paravertebral masses that may exhibit fat attenuation or signal. Hiatal and paraesophageal hernias are common abnormalities in which the stomach herniates into the thorax through the esophageal hiatus. Morgagni hernias occur through an anterior diaphragmatic defect and typically contain omental fat but may also contain liver and bowel. As with other abnormalities of the mediastinum, these lesions may first be identified on chest radiography. However, correlation with pertinent clinical history and cross-sectional imaging, typically contrast-enhanced computed tomography, is necessary for definitive diagnosis.