Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link
Quick Facts

Chronic Lymphocytic Leukemia (CLL)


The Manual's Editorial Staff

Last full review/revision Jan 2020| Content last modified Jan 2020
Click here for the Professional Version
Get the full details

What is leukemia?

Leukemia is a cancer of white blood cells. White blood cells have many jobs, including helping your body's immune system fight off infection. White blood cells form in your bone marrow, the spongy tissue inside your bones.

With leukemia, you have a very high white blood cell count. However, the cancerous white blood cells don't work properly, so you're likely to get infections. Those infections may be life-threatening.

Also, the cancerous white blood cells fill up your bone marrow so it can't make normal blood cells such as:

There are many different types of white blood cells but only 2 main types of leukemia:

  • Lymphocytic leukemia: cancer of lymphocytes, which are one type of white blood cell

  • Myelogenous leukemia: cancer of all the other types of white blood cells

Lymphocytic and myelogenous leukemia can be acute or chronic:

  • Acute: cancer of young cells that spreads quickly and can cause death in 3 to 6 months if untreated

  • Chronic: cancer of mature cells that spreads more slowly

What is chronic lymphocytic leukemia (CLL)?

Chronic lymphocytic leukemia (CLL) is a type of white blood cell cancer that affects lymphocytes, which normally help your body fight infections. In CLL, your lymphocytes turn into cancer cells. These cancer cells take the place of healthy lymphocytes in your blood, bone marrow, and lymph nodes (pea-sized organs throughout your body that help fight off infections).

  • CLL is the most common type of leukemia, usually occurring in adults over 60 and more likely to affect men than women

  • CLL doesn't occur in children

  • You may have no symptoms, or you may have general symptoms such as tiredness, no appetite, weight loss, and swollen lymph nodes

  • To tell if you have CLL, doctors do blood tests and test your bone marrow

  • Chronic lymphocytic leukemia grows very slowly and may not need treatment for many years

  • People with CLL often live 10 to 20 years or more after doctors find the disease

Types of CLL include:

  • B-cell leukemia—this is the most common

  • Hairy cell leukemia

  • T-cell leukemia

What are the symptoms of CLL?

Most people have no symptoms at first.

Later symptoms may include:

  • Swollen lymph nodes (pea-sized organs throughout the body that help fight off infections)

  • Feeling weak and tired

  • Not being hungry and losing weight

  • Shortness of breath when you exercise

  • A feeling of fullness in your belly area (from a swollen liver and spleen)

  • Paleness

  • Bruising easily

You may be more likely to get other cancers, such as skin or lung cancers.

How can doctors tell if I have CLL?

To tell if you have CLL, doctors will:

Sometimes doctors find out that you have CLL when they do blood tests for other health problems.

How do doctors treat CLL?

You may not need any treatment for years.

When you do need treatment, it may include:

  • Corticosteroids

  • Monoclonal antibodies (medicines that help your immune system fight your cancer)

Doctors may also give you treatments for your symptoms, including:

  • Blood transfusions

  • Medicines to help you form more red blood cells

  • Platelet transfusions, if your platelets are low (platelets are blood cells that help your blood clot)

  • Antibiotics for infections

  • Radiation therapy for discomfort from a swollen liver or spleen

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version
Others also read

Test your knowledge

Loss of Smell
Anosmia is the total loss of smell. Most people with anosmia can taste sweet, sour, salty, and bitter substances but cannot distinguish among specific flavors. This is because the sense of smell makes it possible to distinguish among flavors, not taste receptors as many people erroneously believe. Which of the following is NOT a common cause of anosmia?
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest

Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID