Encyclopedia / S / Sarcoidosis


What Is Sarcoidosis?

Sarcoidosis is a relatively common disease characterized by an accumulation of inflammatory cells in various tissues throughout the body, most often in the lungs, lymph nodes, eyes, and skin. Symptoms depend on which organs are affected; in many cases no symptoms appear at all.

Many cases of sarcoidosis subside spontaneously within two or three years; about 40 percent of cases will respond to treatment and only 10 percent will progress to long-term or chronic sarcoidosis. The most serious manifestations of sarcoidosis result from damage to the heart, eyes, and lungs. Symptoms may be relieved with corticosteroid drugs; however, since the disease may be mild and most cases subside even without treatment, the decision to prescribe corticosteroids is based upon the likelihood of complications developing in the lungs, eyes, or other organs. Sarcoidosis is more common between the ages of 20 and 40, although it may strike anyone at any age. In the United States, African Americans are affected more frequently and have more serious complications than whites.

Who Gets Sarcoidosis?

The frequency of sarcoidosis (the percentage of a population infected at a given time) is largely unknown because many cases are asymptomatic and never reported. Often, sarcoidosis is discovered by a chest x-ray done for other purposes. Unlike most lung diseases, sarcoidosis actually occurs more frequently in nonsmokers than smokers. It is not clear why.

The frequency of sarcoidosis varies from place to place. In some geographical areas it is high, and in others it is low. Within a geographical area, the frequency and course of the disease vary considerably among racial groups. In the United States, various studies have shown that sarcoidosis occurs in 10–80 of every 100,000 African Americans, compared to less than 8 of every 100,000 Caucasians. African American women develop sarcoidosis twice as often as African American men. Caucasian women and men are equally likely to develop it. The highest prevalence of sarcoidosis occurs in people ages 25 to 34.


  • Sarcoidosis may cause no symptoms.

  • Fatigue, aching muscles, general feeling of poor health.

  • Fever.

  • Shortness of breath, dry cough, hoarseness, wheezing.

  • Swollen lymph nodes.

  • Blurred vision; painful, red, dry eyes; aversion to light (photophobia).

  • Painful joints.

  • Loss of appetite leading to weight loss.

  • Reddish or brownish skin spots on the forearms, face, or legs; swollen bluish purple areas on the face; red, tender nodules on the skin.

  • Whether or not symptoms appear, chest x-rays almost always reveal abnormalities.

  • The percentage of cases that resolve decreases as the stage increases. Generally, the older the patient is, the more likely the sarcoidosis will become chronic and lead to fibrosis (scarred lung tissue).

Causes/Risk Factors

  • The cause of sarcoidosis is unknown, but it is thought to be an autoimmune disorder (the body’s immune system attacks its own tissues).
  • Sometimes sarcoidosis and tuberculosis occur simultaneously, suggesting they may have the same cause. Though it may be that a patient with sarcoidosis has a suppressed immune system, making them more susceptible to tuberculosis.
  • Familial sarcoidosis occasionally occurs, suggesting that there may be an inherited genetic component.


  • Diagnosis is suspected from patient history, physical examination, and chest x-ray. Because most sarcoidosis cases involve the lungs and thoracic lymph nodes, a chest x-ray is one of the most helpful diagnostic tools.
  • Confirmation of the diagnosis requires a biopsy, often of lung tissue obtained by bronchoscopy (the passage of a thin, flexible viewing tube through the mouth and throat into the lungs).
  • Skin lesions or other affected sites may be biopsied, though these tissue samples have a higher false positive rate than lung biopsy.
  • Lung function tests can help determine severity. One of the most common tests uses a spirometer. The patient breathes into a machine that measures changes in the size of the lungs as the person inhales and exhales. It also indicates whether or not there is any obstruction in airflow.
  • Electrocardiograms (ECGs) are often performed to rule out rhythm disturbances caused by sarcoid involvement of the heart.
  • Eye exam and blood tests (including liver, kidney, and calcium) may also be performed.


  • About 60% to 80% of sarcoidosis cases are self-limiting, meaning that they disappear, at least partially, without intervention, usually within 5 years. If sarcoidosis does not disappear, it either remains stable or progresses.
  • Corticosteroid drugs such as prednisone are prescribed to reduce inflammation and relieve symptoms. When the lungs are involved, such therapy may be sustained for a year or more, then withdrawn to see if spontaneous remission has occurred. Relapses may require indefinite steroid therapy.
  • Methotrexate may be used in patients intolerant of or who do not respond to steroids. Azathioprine is another commonly used drug in steroid resistant or intolerant cases.
  • Hydroxychloroquine (a drug usually used to treat malaria) is often useful in treating skin lesions.
  • Newer methods of treatment are occasionally used, especially if corticosteroids don’t improve symptoms. These include drugs such as infliximab and adalimumab that block TNF, an inflammatory mediator in the body.
  • If a patient has unusually high levels of calcium in the blood (hypercalcemia), which is fairly uncommon, it may be advisable to avoid calcium-rich foods.


There is no known way to prevent sarcoidosis.

When To Call Your Doctor

Call a doctor if you develop persistent shortness of breath, cough, unexplained weight loss, or other symptoms of sarcoidosis.

Reviewed by Allen J. Blaivas, D.O., Division of Pulmonary, Critical Care, and Sleep Medicine, VA New Jersey Health Care System, Clinical Assistant Professor, Rutgers New Jersey Medical School, East Orange, NJ. Review provided by VeriMed Healthcare Network.