Idiopathic hilar fibrosis is a disorder caused by an excessive fibrotic reaction in the mediastinum. The structures of the mediastinum include the heart, great vessels, trachea, esophagus, and lymph nodes. This condition is a subtype of mediastinal fibrosis that is localized to the hilum of either or both lungs. Fibrosis thickens the walls of the pulmonary veins or arteries and can cause bronchial strictures. This can compromise the mediastinal structures, including the airways.

Patients with hilar fibrosis typically present at younger ages than with typical mediastinal fibrosis. The etiology of hilar fibrosis is unknown, but most cases of fibrosing mediastinitis are believed to be secondary to histoplasmosis. Some cases have been associated with tuberculosis.

Clinical presentation and prognosis of idiopathic hilar fibrosis is variable and depends on the structures involved. Patients may have pleural thickening, tracheobronchial narrowing, and obstruction, compression, or stenosis of the pulmonary vessels. This can result in dyspnea, hemoptysis, and pulmonary hypertension. Asymptomatic patients often present with incidental imaging findings of an unknown mediastinal mass.

Asymptomatic patients can safely be monitored and often have a good prognosis with little progression of their fibrosis. Symptomatic patients often have more advanced disease progression and are difficult to manage. Bilateral involvement is associated with higher mortality.

Treatment depends on the affected mediastinal structures, the severity of the scarring, and, in some cases, the cause of the condition.