Musculoskeletal and other extrapulmonary disorders in sarcoidosis.

Sarcoidosis is a multisystemic inflammatory disease, still of unknown origin, characterized by epithelioid non-caseating granuloma in all affected organs. Granuloma formation is lead by a Th1-type response. The exact mechanism that leads to either progression or spontaneous resolution of the disease is not known. Familial aggregation, and the variations in presentation and severity of sarcoidosis according to ethnic background, are suggestive of a polygenic origin that is still to be determined. The contribution of environmental factors, as well as their interactions with genetic factors, remains to be demonstrated. The clinical presentation, musculoskeletal and other extrapulmonary disorders, as well as patients work-up, are reviewed. Sarcoidosis is often a benign disease. Corticosteroids, either alone or in association with other drugs, are still the mainstay of treatment. Defining clearly who will need treatment and what treatment to be used in a particular patient remains controversial.