Fibrosing Mediastinitis

Fibrosing mediastinitis (FM) is due to abnormal proliferation of collagen and fibrous tissue in the mediastinum. It can present either focally or diffusely with the latter type involving multiple mediastinal compartments. Causes are either idiopathic or secondary to granulomatous infection (Histoplasmosis in the United States). 

FM is the most common benign cause of SVC obstruction. Imaging findings include a hilar or mediastinal mass causing mediastinal widening. The right paratracheal region is the most common location for occurrence of a mass. Focal FM tends to have calcified masses whereas calcification is less common in diffuse FM. 

Differential considerations include:

• lymphoma
• bronchogenic carcinoma - usually older patient, doesn't calcify

REFERENCES
Rossi SE, McAdams HP, Rosado-de-Christenson ML, et al. Fibrosing mediastinitis. Radiographics 2001;21:737-57.