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General Information about Sarcoidosis

Sarcoidosis Week

What causes sarcoidosis?

The pathogenesis of sarcoidosis remains unknown, but the role of the immune system in creating non-caseating granulomas is clearly a critical component of developing sarcoidosis. There are likely genetic predispositions to developing sarcoidosis, although the nature and type of genetic abnormalities are not known. There has been long-standing suspicion that infectious agents such as viruses or bacteria play a role in causing sarcoidosis, but this has not been scientifically proven. Environmental causes, such as allergens or other non-infectious particles, may play a role in activating a patient’s immune system leading to non-caseating granulomas and sarcoidosis. That the cause(s) of sarcoidosis is unclear has limited therapeutic advances in treating this disease.

Who gets sarcoidosis?

Sarcoidosis is a relatively rare disease, with a higher incidence of sarcoid in African-Americans (~35 cases per 100,000) as well as in northern European countries. Sarcoidosis occurs more commonly in women than in men. Sarcoidosis can occur at any age, but has the highest incidence between 30-50 years of age. There is no described association between socioeconomic status and sarcoid incidence. There is a familial association, underscoring the presumed genetic predisposition for sarcoidosis, as family members of patients with sarcoidosis have increased risk of developing sarcoidosis themselves. Finally, sarcoidosis is not contagious or transmittable from one person to another.

What are symptoms of sarcoidosis?

Because sarcoidosis can affect many different tissues and organ systems, the symptoms of sarcoid can be quite variable. Systemic symptoms such as fever, polyarthalgias, and erythema nodosum, coupled with hilar adenoapathy on chest imaging, characterize Lofgren syndrome, an acute presentation of sarcoidosis associated with an excellent prognosis. When sarcoid involves specific organs, it can result in symptoms derived from organ dysfunction and disease. The lungs are commonly affected by sarcoidosis, with an estimated 90% of patients developing pulmonary involvement. Pulmonary fibrosis can occur in 20-25% of patients, resulting in shortness of breath, cough, and other pulmonary symptoms.

How is sarcoidosis diagnosed?

There is no single laboratory or imaging study that definitively diagnoses sarcoidosis. Clinical suspicion is critical for diagnosing sarcoid, and the constellation of consistent symptoms and supporting diagnostic evidence (such as chest x-ray changes suggestive of sarcoid) is necessary to diagnose this condition. Serum angiotensin-converting enzyme (ACE) levels are still frequently measured, but are not helpful clinically due to the poor sensitivity and specificity of this test. Chest x-ray and pulmonary function tests are appropriate for the initial evaluation of a patient with suspected sarcoidosis. Biopsy of an affected organ or tissue can demonstrate non-caseating granulomas which, in the appropriate clinical setting, can confirm the diagnosis of sarcoid. Advanced radiography for diagnosing sarcoid, such as combined CT and positron emission tompgraphy (PET) imaging to guide biopsy of active sarcoid lesions, is an increasingly frequent component of the diagnostic evaluation of sarcoidosis.

How is sarcoidosis treated?

Not all patients with sarcoidosis require treatment, as some forms of sarcoidosis either resolve spontaneously (such as Lofgren syndrome) or plateau with regard to symptoms progression. When treatment is indicated, corticosteroids are first-line therapy. Corticosteroids are typically prescribed at a high dose for a prolonged course of 6-12 months while following the patient’s response to therapy. Other immunosuppressive medications have been used as alternatives to corticosteroids in some cases, but the evidence regarding their efficacy is limited. Lung transplantation is a final option for patients with end-stage respiratory disease from sarcoidosis.

Better understanding of the pathogenesis of sarcoidosis could lead to more targeted, effective interventions for treating this disease.

Quick Facts About Sarcoidosis

  1. Prevalence estimated at close to 200,000 in the United States

  2. Spontaneous remission occurs in 60-70% of patients; disease mortality is 1-5% (most common cause of death is respiratory failure) [Hunninghake et al. (1999)]. Among African Americans, the most affected U.S. group, the estimated lifetime risk of developing sarcoidosis might be as high as 2 percent.

  3. There is no cure for sarcoidosis, but the disease may get better on its own over time or with drug therapy. Drug treatments are used to relieve symptoms, reduce the inflammation of the affected tissues, reduce the impact of granuloma development, and may prevent the development of lung fibrosis or other irreversible organ damage.

  4. There is no evidence that pharmacological therapy prevents disease progression