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Chronic Lymphocytic Leukemia (CLL)
Many people with chronic lymphocytic leukemia (CLL) do not have any symptoms when it is diagnosed.
CLL is often found when blood tests show a high number of lymphocytes (a type of white blood cell). This is usually discovered when a doctor orders blood tests during a routine checkup or for some other health problem. If CLL does cause symptoms, they can include like fatigue, weight loss, fever, and swollen lymph nodes.
Even when people with CLL have symptoms, they’re often vague and can be caused by other things.
Symptoms can include:
Many of the signs and symptoms of more advanced CLL happen because the leukemia cells replace the bone marrow's normal blood-making cells. As a result, people don't have enough red blood cells, normal white blood cells, and blood platelets.
A shortage of red blood cells (anemia) can lead to:
A shortage of normal white blood cells (leukopenia) increases the risk of infections.
You might also hear the term neutropenia. This refers to low levels of neutrophils (a type of granulocyte needed to fight bacterial infections).
People with CLL may have very high white blood cell counts because of excess numbers of lymphocytes (lymphocytosis), but the leukemia cells don’t fight infection the way normal white blood cells do.
A shortage of blood platelets (thrombocytopenia) can lead to:
CLL is a cancer of B lymphocytes, which normally make antibodies that help fight infections. In some people, the CLL cells make abnormal antibodies that attack normal blood cells. This is known as autoimmunity. It can lead to low blood counts:
The symptoms and signs above may be caused by CLL, but they can also be caused by other conditions. Still, if you have any of these problems, it’s important to see a doctor so the cause can be found and treated if needed.
Developed by the American Cancer Society medical and editorial content team with medical review and contribution by the American Society of Clinical Oncology (ASCO).
Awan FT, Byrd JC. Chapter 99: Chronic lymphocytic leukemia. In: Niederhuber JE, Armitage JO, Doroshow JH, Kastan MB, Tepper JE, eds. Abeloff's Clinical Oncology. 6th ed. Philadelphia, Pa: Elsevier; 2020.
Rai KR, Stilgenbauer S. Clinical features and diagnosis of chronic lymphocytic leukemia/small lymphocytic lymphoma. UpToDate. 2024. Accessed at https://www.uptodate.com/contents/clinical-features-and-diagnosis-of-chronic-lymphocytic-leukemia-small-lymphocytic-lymphoma on February 6, 2025.
Last Revised: March 20, 2025
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