What is Sarcoidosis?

Sarcoidosis (sar-coy-DOE-sis) is a disease of unknown cause in which inflammatory cells clump together and form tiny lumps of cells in various organs and tissues of the body. These lumps are called granulomas (gran-yu-LO-mas). Sarcoidosis most often affects the lungs and its hilar lymph nodes but can also involve other areas of the body including the eyes, skin, sinuses, liver, kidneys, brain and heart. Sarcoidosis varies in how active and how severe it is for each person and over time. The granulomas, when active, can cause short term and/or long-term damage to the organ involved. This fact sheet provides a general overview of sarcoidosis. For more information about treatment of sarcoidosis, see “Treatment of Sarcoidosis”.

Chronic inflammation and damage leads to symptoms and occasionally, permanent loss of function of the involved tissues/organ. When sarcoidosis affects the lungs (pulmonary sarcoidosis), the disease can reduce the amount of air the lungs can hold and cause abnormal stiffness, called “restriction,” of the lungs. This results in breathing problems that can interfere with daily activities.

What causes sarcoidosis?

The cause of sarcoidosis is unknown. Sarcoidosis is not contagious, and it is not a cancer. People with a family member who has sarcoidosis have a low risk (1 in 20) of also getting the disease.

What are the signs and symptoms of sarcoidosis?

Many people with sarcoidosis do not have any symptoms. Others have only vague symptoms that can be seen in many other illnesses, such as weight loss, fever, loss of appetite, depression, night sweats, and sleep problems. Signs and symptoms that may come from problems with a specific organ include:

• Lungs: Shortness of breath, wheezing or dry cough that may lessen or go away over time in some people, but remain in others.
• Lymph nodes: Enlarged and sometimes tender lymph nodes, most often in the neck and chest, but sometimes under the chin, arm pits or groin.
• Eyes: Burning, itching, tearing, redness, sensitivity to light, dryness, seeing black spots, blurred vision, reduced color vision, and, in rare cases, blindness.
• Skin: Bumps, ulcers, or rarely, flat areas of discolored skin that appear mostly near the nose or eyes or on the back, arm, legs and scalp. Painful and tender discreet reddened bumps called erythema nodosum can suddenly appear on the ankles and shins. This rash is most often seen in younger patients and can be associated with joint pains, fever and enlarged nodes in the chest called Lofgren’s syndrome.
• Bones and Joints: Bone lumps (nodules), causing pain in the hands and feet, and/or other swelling of ankles or other joints.
• Spleen and Liver: There can be pain in the upper abdomen, under the ribs on the right (liver) or left (spleen). 
• Heart: Shortness of breath with activity and swelling in the legs. One may have an irregular, fast or slow heart beat at times, or pass out without warning. Sometimes a pacemaker may be required.
• The Nervous System: Headaches, vision problems, numbness, weakness, or loss of movement of arms or legs, drooping of one side of the face, pain or a “pins and needles” feeling.
• Fatigue is a common problem, seen in more than half of patients.

How is sarcoidosis diagnosed?

Since sarcoidosis can affect one or more parts of the body, the signs and symptoms depend on the tissue/organs involved. Some people with the disease do not have any symptoms and it may be noticed by chance when they are being seen for other problems. Other people may be hard to diagnose because the symptoms they have are not very specific. But certain clinical features such as the erythema nodosum, or rash or eye findings may lead a healthcare provider to suspect sarcoidosis.

There is no specific blood test to diagnose sarcoidosis. Sarcoidosis can mimic infection and several other diseases. Hence the diagnosis requires checking for other causes of symptoms and disproving infection, cancer and other diseases as a cause.

Your healthcare provider will do a history and physical exam to look for signs of sarcoidosis and rule out other diseases. A number of other studies may be done including:

• A chest X-ray to look for enlarged lymph nodes and small round spots, called granulomas, in the lungs.
• Pulmonary function tests to measure how well the lungs work. For more information, see ATS Patient Information Series fact sheet “Lung Function Testing.”
• A CT scan of the chest may show enlarged lymph nodes and scars in the lungs that a regular chest X-ray may not.
• A bronchoscopy and bronchoalveolar lavage. A bronchoscopy is a test in which a flexible tube is put into the airways and mucus fluid samples can be suctioned out. This fluid is called bronchoalveolar lavage (BAL) and the cells in it can be examined under the microscope. For more information see ATS Patient Information Series fact sheet “Flexible Bronchoscopy.”
• A tissue biopsy. Taking a small piece of tissue to examine under a microscope to look for signs of disease. This can be obtained through surgery or a bronchoscopy (endobronchial or transbronchial biopsies). A special device with ultrasound guided biopsy via bronchoscopy (EBUS) may also be used to get samples from the lung.
• An eye exam with a specially lighted tool allows the doctor to look inside the eye for possible signs of sarcoidosis.
• Blood tests can show abnormal function of the involved organs such as the liver, kidney, bone marrow and calcium levels.
• An electrocardiogram (EKG) is a test that records a tracing of the electrical activity of the heart. It shows the rate of heart beats. It may show how regularly the heart beats and may show if there is any strain on the heart, irregular rhythm, or heart blocks.
• An MRI of the heart is a type of imaging scan that can detect heart involvement by sarcoidosis earlier than an EKG. It can also be helpful to identify areas in the heart to biopsy, if needed.
• PET scan may detect sarcoidosis in various parts of the body and may predict response to treatment. A dedicated cardiac PET scan can be done to detect sarcoidosis in the heart.

Definitive diagnosis requires the provider to put together information from the history, physical exam, and laboratory results that show granulomas (characteristic features of sarcoidosis).

How serious is sarcoidosis?

The course of sarcoidosis varies greatly among people and over time for an individual. In many cases, sarcoidosis is mild and self-limited. Symptoms may go away within a few years without treatment.

Sarcoidosis starts with active, ongoing inflammation. Granulomas (lumps) form and grow. Symptoms develop and scar tissue can form in the organs where the granulomas are growing. In most patients, the inflammation decreases, and the granulomas stay the same size or shrink within a few years. But any old scars will remain and can still cause symptoms. However, for some patients, sarcoidosis can become chronic, lasting lifelong.

The severe form of sarcoidosis slowly worsens over a period of years, and can cause permanent organ damage. Treatment can help, but the disease may still leave scar tissue in the lungs, skin, eyes, sinuses, heart of other organs. Between 20 and 30 percent of people with pulmonary sarcoidosis end up with permanent lung damage. The scarring from sarcoidosis is often in upper portions of the lungs.

The lungs are at risk of infection due to fungus or bacteria, including mycobacteria. A “fungus ball” can form and a person can develop bleeding (cough up blood).

There are two reasons to treat sarcoidosis:

• Concern for developing organ damage (including respiratory failure) and/or
• To improve quality of life.

Treatment is aimed at maintaining good foundation of the organ involved, reducing symptoms, improving quality of life, and preventing organ damage. Talk with your healthcare provider about how sarcoidosis is affecting your health and what treatment you may need. See “Treatment of Sarcoidosis” for more information.

RX Action Steps

• Talk with your healthcare provider about whether you need treatment for sarcoidosis and what options you have.
• Do not smoke and try to avoid being around tobacco smoke.
• Take action to stay health and watch for early changes with sarcoidosis.

Additional Lung Health Information

Foundation for Sarcoidosis Research

National Heart, Lung and Blood Institute (also available in Spanish)

American Lung Association of Canada

Online Version Updated April 2025

Author: Ganesh Raghu, MD

Reviewers: Robin Gross, MD, Marianna Sockrider, MD, DrPH, Hrishikesh S. Kulkarni, MD, Ginger Spitzer, Rogert Baughman, MD

This information is a public service of the American Thoracic Society. The content is for educational purposes only. It should not be used as a substitute for the medical advice of one’s own health care provider.