Sarcoidosis is a chronic multisystemic disease whose cause is not well understood. Peak incidence occurs among people between 20 and 29 years of age, and the disease has higher prevalences among women and black people than in the general population. The lungs are the most frequently affected organ, accounting for 90% of cases, but only 50% are symptomatic. Diagnosis requires histopathological confirmation, except in patients who have the Löfgren triad. Characteristic histology consists of noncaseating granulomas with giant multinucleated cells. Radiological manifestations of pulmonary disease due to sarcoidosis are extensive. They include typical lymphadenopathy, especially bilateral hilar lymphadenopathy, and right paratracheal lymphadenopathy; parenchymal manifestations including perilymphatic nodules, bilateral perihilar opacities, and changes due to fibrosis; atypical lymphadenopathy including unilateral lymphadenopathy and asymmetric lymphadenopathy; and parenchymal manifestations including alveolar sarcoidosis, lung masses, airway diseases, pleurisy and other manifestations such as mycetoma. Thirty percent of patients have extrapulmonary involvement, most frequently hepatic (40% - 60%). The prognoses for patients with this disease is good, and remission occurs in 66% of patients. The Scadding criteria for chest x-rays is currently used to stage sarcoidosis, but CT scan studies have shown findings such as centrilobular nodules, consolidation, ground glass patterns and thickening of interlobular septa that correlate with reversibility of imaging alterations.