Sarcoidosis
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Introduction
Sarcoidosis is a systemic disease of unknown cause, characterized by noncaseating granulomas. It is an interstitial (restrictive) lung disease.
Prevalence is higher in women than men. Blacks are 10x more susceptible than whites, while the disease is very rare amongst Asians.
Most cases occur in the winter or early spring.
The Case of...
a simple case introducing clincial presentation and calling for a differential diagnosis to get students thinking.
Causes and Risk Factors
Certain HLA genotypes appear involved.
There is no unequivocal evidence that infectious agents are involved, though mycobacteria, Propionibacterium acnes, and Rickettsia specias are all canditates.
Pathophysiology
Sarcoidosis appears to be the result of disorder immune regulation in genetically susceptible people exposed to certain environmental agents.
CD4+ cells undergo antigen-driven proliferation, and TH1 production of IL-2 and IFNγ result in T cell and macrophage expansion, respectively.
Macrophages and other cells produce large amounts of cytokines, such as IL-8, TNF, and MIP-1alpha.
Involved tissues show aggregates of tightly clustered epitheliod cells, often with giant cells involved.
Lymph nodes are almost always involved, and the spleen and liver commonly are as well.
Signs and Symptoms
- history
- physical exam
History
History
People usually seek answers for respiratory problems such as shortness of breath, cough, chest pain, or hemoptysis, or for constitutional problems such as fever, fatigue, weight loss, anorexia, or night sweats.
Physical Exam
Cardiovascular
- pulmonary hypertension: loud S2, high JVP, pulsatile liver
Respiratory: most commonly nothing; can also hear fine or coarse crackles
Peripheral lymphadenopathy may also be present, as can cutanous signs, eye involvement, splenomegaly, or hepatomegaly.
Investigations
- lab investigations
- diagnostic imaging
Lab Investigations
nonspecific
peripheral blood eosinophilia is commonly seen.
TNF levels, and increased CD4/CD8 ratio in bronchoalveolar fluid are a marker of disease activity.
Anergy to common antigens such as Candida or PPD are common.
Diagnostic Imaging
Bilateral hilar lymphadenopathy or lung involvement is present in 90% of cases.
Differential Diagnosis
Mycobacteria or fungal infections and beryllosis can also produce noncaseating granulomas, making sarcoidosis a disease of exclusion.
Treatments
Steroids and methotrexate may be used to reduce to inflammation.
Treat 4-6 months of high dose steroids, with a very slow taper.
TNF inhibitors may be used as well.
Consequences and Course
Sarcoidosis is most often diagnosed incidentally, and most people are asymptomatic.
Stage I:
Stage II:
Stage III:
Stage IV:
Sarcoidosis is unpredictable, with progressive chronicity, remissions of various lengths, or disappearance of disease all
possible.
Twenty percent have some permanent loss of lung function or visual impairment.
The remaining 10-15% usually die of progressive pulmonary fibrosis and cor pulmonale.
People with adenopathy do the best.
Resources and References
Topic Development
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