More about Sarcoidosis - What are granulomas?

Hi Everybody,

Lizzie asked me to write a little bit about granulomas and sarcoidosis.

A patient handout found on healthcommunities.com gives a slightly different explanation of sarcoidosis (see below for a link):

"Sarcoidosis is a disease caused by an abnormal immune system reaction. In patients who have sarcoidosis, clumps of immune cells called granulomas form in the organs."

What are Granulomas?

Short Version:

Granulomas are formed by our immune system in an attempt to protect our body from foreign invaders. Cells which first form the center of the granuloma engulf or swallow the foreign substance, and other immune cells and fibrous cells surround the center cells to wall the foreign substance off from the rest of the body.

Long Version:

Granulomas can be formed by our immune system when there is inflammation lasting longer than two weeks (chronic inflammation).

1. During the acute stage of inflammation (the first two weeks) immune cells called macrophages and neutrophils attempt to destroy the foreign invaders.
2. If the inflammation becomes chronic and the immune system cannot protect our body from tissue damage macrophages morph into cells called epithelioid cells or join with other macrophages to form giant cells. These two types of cells cannot destroy foreign substances like macrophages can, but they can swallow or engulf them. The epithelioid cells and giant cells make up the center of the granuloma.
3. The center is then surrounded by lymphocytes (white blood cells) and can be covered by fibrous collagen creating a more stable structure, and then possibly calcified with calcium carbonate and calcium phosphate.

End of long version.


There is an excellent article on Sarcoidosis on "http://www.pulmonologychannel.com/sarcoidosis/index.shtml" as well as a printable "Questions to ask your doctor about sarcoidosis" if you want more information.

The rest of this information was found in McCance and Huether's Pathophysiology, the Biologic Basis for Disease in Adults and Children, Fifth Edition.

Jeanne