Fibrosing mediastinitis

Fibrosing mediastinitis is a rare benign disorder caused by proliferation o f acellular collagen and fibrous tissue within the mediastinum. Although ma ny cases are idiopathic, many (and perhaps most) cases in the United States are thought to be caused by an abnormal immunologic response to Histoplasm a capsulatum infection. Affected patients are typically young and present w ith signs and symptoms of obstruction or compression of the superior vena c ava, pulmonary veins or arteries, central airways, or esophagus. There may be two types of fibrosing mediastinitis: focal and diffuse. The focal type usually manifests on computed tomographic (CT) or magnetic resonance (MR) i mages as a localized, calcified mass in the paratracheal or subcarinal regi ons of the mediastinum or in the pulmonary hila. The diffuse type manifests on CT or MR images as a diffusely infiltrating, often noncalcified mass th at affects multiple mediastinal compartments. CT and MR imaging play a vita l role in the diagnosis and management of fibrosing mediastinitis.