Chronic Lymphocytic Leukemia (CLL) is a type of leukemia (there are several). Leukemia is a cancer that generates in the bone marrow, and then travels to the blood stream. It typically stays in the blood stream for several years before it progresses to other organs (metastasis). Because it is primarily in the bone marrow and bloodstream, CLL is often referred to as a "liquid tumor," as opposed to a "solid tumor," which is a mass of tissue that can usually be felt on the body.
When CLL is first beginning to develop, some cells in the bone marrow, white blood cells called "lymphocytes," begin to mature abnormally. These abnormal lymphocytes are called "leukemia cells," and they do not die when they should. Leukemia cells continue to build up in the bone marrow until there are so many they are pushed out into the bloodstream. It may take several years for this to happen, and you may not feel any symptoms at all while the leukemia cells are building up. That is because the leukemia cells themselves are not problematic and will not hurt you. The problem is that leukemia cells do not die when they should, and as they continue to build up, they interfere with the functioning of the normal cells that your body needs.
Distinguishing CLL from the other types of leukemia, we can break down the name of the cancer. "Chronic" means that the cancer progresses more slowly than other types, and symptoms may not be noticeable for awhile. It also means that people may live for many years with the disease. "Lymphocytic" refers to the type of cells where the cancer originates. Other common types develop in the myeloid cells. "Leukemia" means the cancer is in the bone marrow and bloodstream.
There are a few different types of CLL, although the most common type originates in the B lymphocytes. The other kinds can be distinguished by doing a test for certain proteins in the blood, or looking at the leukemia cells under a microscope. Your doctor will run these tests for you and discuss your specific disease.
References:
What is chronic lymphocytic leukemia? 2015. Retrieved April 4, 2015, from http://www.cancer.org/cancer/leukemia-chroniclymphocyticcll/detailedguide/leukemia-chronic-lymphocytic-what-is-cll
