Sarcoidosis: a review for the internist

Sarcoidosis is a systemic granulomatous lung disease of unknown origin affecting people of any age, mainly young adults. The disease is extremely heterogeneous with an unpredictable clinical course. Different phenotypes have been identified: an acute syndrome can be distinguished from subacute and chronic variants. About 20% of patients are chronically progressive and may develop lung fibrosis. Sarcoidosis usually involves the lungs and thoracic lymph nodes, although the skin, eyes, bones, liver, spleen, heart, upper respiratory tract and nervous system can also be affected. No reliable indicators of clinical outcome are available, and there is no single serological biomarker with demonstrated unequivocal diagnostic and prognostic value. Diagnosis requires histological confirmation although a presumptive diagnosis may be acceptable in special conditions. This review examines the diagnostic approach to sarcoidosis involving a multidisciplinary team of specialists in which the internist has the task of identifying all pulmonary and extrapulmonary localizations of the disease and of managing complications and comorbidities.