Sarcoidosis

Sarcoidosis is a systemic disease of unknown etiology, characterized by noncaseating epithelioid cell granulomas. Patients with sarcoidosis are frequently asymptomatic and may be diagnosed incidentally because of an abnormal imaging study. Sarcoidosis is a diagnosis of exclusion that warrants pathological confirmation in all cases. The distribution of granulomas in the lungs is characteristic and correlates with imaging findings; non-necrotizing granulomas classically exhibit a perilymphatic distribution. On chest radiography, the presence of bilateral hilar and right paratracheal lymphadenopathy, particularly in a young asymptomatic patient, should raise the possibility of sarcoidosis. On CT, a perilymphatic distribution (peribronchovascular, subpleural, septal) of abnormalities in the appropriate clinical context is highly specific for sarcoidosis.