Nonmalignant causes of SVCS include mediastinal fibrosis, aortic aneurysm, vasculitis, infections, benign mediastinal tumors, and thrombosis related to the presence of central vein catheters.

This sound is similar to “crackles” that can be heard in the lungs in patients with pulmonary fibrosis. Mediastinal emphysema can occur after esophageal rupture or after cardiac surgery.

Stage I: Hilar/mediastinal lymphadenopathy not associated ... show an increased tendency toward the development of pulmonary fibrosis. Spontaneous remission occurs in 30% of cases.