Understanding Sarcoidosis

Sarcoidosis is a disease caused by inflammation. Scientists believe sarcoidosis is an immune system disease brought on by a failure of the body's natural defense system. It is not contagious.

Sarcoidosis can attack any part of the body—inside or out—but 90 percent of the cases affect the lungs. When sarcoidosis appears in the lungs it is called pulmonary sarcoidosis.

Sarcoidosis appears as small patches of inflamed cells. It can cause different symptoms depending on where it appears. On the skin, it may look like a scaly rash or red bumps. In the eyes, it can cause soreness. If it affects muscles, it can cause swelling and soreness. In the lungs, it can cause a dry cough, mild chest pain, or shortness of breath.

How Serious Is Sarcoidosis?

Nobody can predict how sarcoidosis will affect one person verses another.  It is not serious in over half the cases. The disease appears briefly and heals naturally, without treatment. Some people don't even realize they have sarcoidosis. However, another 20-30 percent of people with pulmonary sarcoidosis end up with permanent lung damage. A small percentage of patients may have chronic sarcoidosis, lasting for many years.

Who Gets Sarcoidosis?

Anyone can get sarcoidosis. It is most common among African Americans and northern European whites, especially Scandinavians. In the U.S., African Americans have a much higher percentage of sarcoidosis than whites, and it is usually much more serious in African Americans.

Sarcoidosis usually affects young adults—people between 20 and 40—but it can affect people older than 60. It is somewhat more common among women than men.

How Does Sarcoidosis Affect the Body?

Sarcoidosis can attack any part of the body—inside or out. It appears as small patches of inflamed cells. Sarcoidosis usually goes away on its own, disappearing without the patient or doctor necessarily noticing it.

When sarcoidosis appears in the lungs it is called "pulmonary sarcoidosis". In pulmonary sarcoidosis, small patches of inflamed cells can appear on the lungs' small air sacs (alveoli), breathing tubes (bronchioles) or lymph nodes. In serious cases of pulmonary sarcoidosis, it can lead to an abnormal formation of scar tissue in the lung, called pulmonary fibrosis. The scar tissue warps the structure of the lung, which can make breathing difficult. It also affects the lungs' ability to move oxygen into the bloodstream.

Ninety percent of cases affect the lungs. Other common sites include:

  • skin
  • liver
  • lymph glands
  • spleen
  • eyes
  • nervous system, including the brain
  • muscles and bones (musculoskeletal system)
  • heart
  • kidneys

What Causes Sarcoidosis?

Nobody yet knows what causes sarcoidosis. Most scientists believe it is a disease of the immune system, where the body's natural defense system does not function properly. Some believe that sarcoidosis might be the result of a respiratory infection caused by a virus. Others blame toxins or allergens in the environment.

Researchers are studying sarcoidosis to understand its cause and many other questions related to the disease.