Rheumatic manifestations of systemic disease: sarcoidosis

Sarcoidosis commonly involves the lungs but also not uncommonly presents as uveitis, arthritis, myositis or neurologic disease. Recognition of the presenting features, organ complications, and immunopathogenesis is important for timely diagnosis and appropriate management.

Current studies support the disorder developing as a consequence of a CD4+ T-cell-mediated response to variable environmental or microbial triggers in the context of one or more determined susceptibility genes including BTNL2, with other genes such as CARD15/NOD2, governing disease severity. Magnetic resonance imaging (MRI) is useful in defining the presence and extent of central nervous system (CNS), osseous, and both skeletal and cardiac muscle disease. Corticosteroids remain the mainstay of therapy; patients with refractory disease may respond to other immunomodulating drugs, including anti-TNF-alpha antibodies but the optimal roles of traditional immunomodulating as well as newer biologic therapies in management are continuing to be defined.

Insights into triggering immune events and susceptibility genes should provide potential new strategies and targets for therapy. The judicious use of MRI in suspected cases can enhance earlier recognition of disease in the CNS, bone, and both skeletal and cardiac muscle to guide diagnostic procedures as well as appropriate treatment.