Sarcoidosis: immunology, rheumatic involvement, and therapeutics

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Sarcoidosis: immunology, rheumatic involvement, and therapeutics

na Barnard, MA*; Lee S. Newman, MD?

*Epidemiologist and Sarcoidosis Research Coordinator, National Jewish Medical

and Research Center, Denver, Colorado, USA; ?Head, Division of Environmental and

Occupational Health Sciences, Department of Medicine, National Jewish Medical

and Research Center, Denver, Colorado, USA, and Professor, Department of

Medicine and Department of Preventive Medicine and Biometrics, University of

Colorado School of Medicine, Denver, Colorado, USA

CURRENT OPINION IN RHEUMATOLOGY 2001;13:84-91

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Sarcoidosis is a systemic granulomatous disorder of unknown cause. It has

protean manifestations and can affect any organ, including bones, joints,

muscles, and vessels. This article reviews the most recent information on the

immunologic and inflammatory pathogenesis of sarcoidosis and its implications

for therapy. Sarcoidosis results from an overexuberant T cell-mediated immune

response to the unknown antigen. This antigen presentation/T cell antigen

recognition event occurs in a microenvironment that is suffused in

proinflammatory cytokines and growth factors that promote cell attraction,

adhesion, permeability changes, further cytokine production, and release. An

amplified cellular immune response ensues, leading to granuloma formation and

fibrosis. The article summarizes the new developments in the medical literature

related to the rheumatologic manifestations and their detection and management

in sarcoidosis patients. Osseous involvement in sarcoidosis is often

underdiagnosed because it can be asymptomatic. New imaging techniques improve

detection. Management of osteoporosis in sarcoidosis patients requires special

attention because these patients often have an underlying disorder in calcium

metabolism that results in hypercalcuria and hypercalcemia. Joint

manifestations, such as the classic Lofgren syndrome with accompanying erythema

nodosum, may be self-limited or may become chronic, presenting an ongoing

therapeutic challenge. Sarcoidosis vasculitis can be devastating, affecting

virtually any vessel in any organ and causing significant morbidity. Muscle

involvement, like the bony involvement, is underdiagnosed. Symptoms of muscle

weakness, aches, tenderness, and fatigue should prompt consideration of occult

sarcoid myositis, often with accompanying neurogenic atrophy. Sarcoidosis

treatment usually starts with a period of observation before pharmacologic

intervention. Corticosteroids remain the first-line therapy. Alternatives to

corticosteroids are often introduced either because of steroid intolerance or in

an attempt to reduce steroid dose and side effects. The advantages and

disadvantages of these second line therapies are reviewed. Medical vigilance,

with attention to new patient symptoms, is important in the management of

sarcoidosis, because of the tendency of this disease to present in so many and

diverse patterns.