Causes of Sarcoidosis

Sarcoidosis is an immune system condition characterized by small patches of inflammation called granulomas, which build up over time in body tissues and can cause damage to organs.

The disorder usually develops in the lungs and lymph nodes, but any organ can be affected. Consequently, it can have a wide range of symptoms, depending on the organs affected and length of time they’ve been affected.

In most cases, sarcoidosis is temporary and will disappear on its own, but sometimes it can become more long-term. In these cases, serious and permanent damage to organs can occur.


Granulomas form as a result of an over-active immune response. Normally, immune cells will mount an inflammatory response when they come in contact with something that could be dangerous, like an infectious bacteria or a toxin — any molecule that can stimulate an immune response is referred to as an antigen.

Typically, the antigen gets destroyed as part of the immune system’s inflammatory response, but in most cases of sarcoidosis, antigen clearing doesn’t happen as it should. The result is that some antigen is left in immune cells, which initiates a pro-inflammatory feedback loop and ultimately results in the formation of a granuloma — a mass of multiple immune cells arranged in a structured, ordered manner.

It’s unclear why this atypical immune response occurs in sarcoidosis patients. Both genetic and environmental factors play a role in determining whether an individual will develop sarcoidosis.


Sarcoidosis tends to run in families, so there is likely a genetic component to the disease. Nearly a dozen individual genetic variations have been linked with an increased risk of sarcoidosis, though no single mutation determines whether or not a person will develop the disease. A family history of the condition does not guarantee that sarcoidosis will appear in a particular individual in a noticeable way.

Certain ethnicities are more likely to develop sarcoidosis than others, and this is believed to be in part attributable to genetic variations among different ethnic populations. Blacks, Puerto Ricans, and people of Scandinavian or Irish descent have among the highest rates of sarcoidosis in the U.S.

Environmental factors

Sarcoidosis usually begins with a triggering event, like an allergic reaction or an infection, which sets the over-active immune response into motion.

Exposure to a variety of different environmental factors, including wood stoves, soil, tree pollen, insecticides, and nanoparticles, has been tied to an increased risk of developing sarcoidosis. People exposed to debris when the U.S. World Trade Center collapsed have also been reported to be at increased risk of sarcoidosis.

Certain professions have also been tied to an increased sarcoidosis risk, including ship workers in the navy, firefighters, educators, and workers involved in hardware, gardening materials, building supplies, and metal work.


Last updated: June 29, 2021


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