Diagnostic criteria for sarcoidosis.

Sarcoidosis is a multiorgan system disease that often presents insidiously. The diagnosis is often made fortuitously upon routine chest radiography or that done for other reasons. Blacks are more commonly affected than whites and age of onset is typically adolescents to young adults. Lung involvement is common and symptoms may include cough, dyspnea and chest pain. Extrapulmonary symptoms may include the skin, joint and eye findings. Bilateral hilar adenopathy is the classic finding on chest radiograph. Anemia or other cell line deficiencies, elevated liver enzymes, hypercalciuria, and EKG abnormalities may also be present. Angiotensin converting enzyme levels may be elevated but are not diagnostic. Histopathological confirmation of noncaseating granulomas is essential for diagnosis. It is generally performed through a biopsy of the most peripheral site possible, although transbronchial biopsy is commonly required. Finally, other possible etiologies must be evaluated and differentiated with a particular emphasis on tuberculosis due to the multiple overlapping symptoms and findings. Newer techniques such as proteomics and transcriptional gene signatures may contribute to the understanding of the pathophysiology of sarcoidosis, and may even serve as diagnostic tools in the future.