A CLL diagnosis requires a B lymphocyte count of 5 billion per liter (or 5,000 per microliter) for 3 months. A doctor needs to use a technique called flow cytometry to confirm a CLL diagnosis.

Chronic lymphocytic leukemia (CLL) occurs when B lymphocytes, a category of white blood cells, divide uncontrollably. Doctors can use several tests to check for characteristics of B lymphocytes that may indicate CLL.

The primary tests doctors use to help diagnose CLL are blood tests and flow cytometry. Blood tests can help doctors see whether you have increased levels of abnormal white blood cells. Flow cytometry allows doctors to see markers on the surface of your blood cells that are characteristic of CLL.

Read on to learn more about how doctors diagnose and stage CLL.

Experts have developed multiple guidelines for diagnosing and treating CLL. One of the most widely used is the International Workshop on Chronic Lymphocytic Leukemia (iwCLL) guidelines.

According to this set of criteria, a diagnosis of CLL requires a B lymphocyte count greater than 5 billion per liter (or 5,000 per microliter) of blood for at least 3 months.

Doctors use many tests to diagnose and stage CLL. Your doctor may start by:

  • reviewing your personal and family medical history
  • performing a physical exam to look for swelling in your belly or lymph nodes
  • asking you about your symptoms and general health

According to the iwCLL guidelines, a CLL diagnosis always requires:

  • blood tests
  • immunophenotyping with flow cytometry

Blood tests and immunotyping

A complete blood count is an essential test for diagnosing CLL. People with CLL have elevated white blood cell counts, specifically elevated B lymphocyte counts. They may have low levels of red blood cells and platelets.

Doctors can confirm a CLL diagnosis using flow cytometry. During this test, a sample of your blood or bone marrow is stained with special dyes and passed through a laser. The results can show your doctor abnormal markers on the surface of your B lymphocytes suggestive of CLL.

What are the markers for CLL?

CLL cells have abnormal proteins on their surface that can help doctors identify cancerous cells with flow cytometry. This specific set of protein markers is known as the immunophenotype. It can help doctors confirm a diagnosis and rule out other leukemias.

Determining the immunophenotype through flow cytometry can also provide insight into how CLL will progress and guide treatment decisions.

Was this helpful?

Other tests

You may receive other tests, including:

The two main staging systems for CLL are the Binet and Rai systems. The Binet system is more common in Europe. The Rai system is more common in the United States.

Rai staging system

The Rai staging system divides CLL into five stages:

0• elevated lymphocyte count
1• elevated lymphocyte count
• enlarged lymph nodes
2• elevated lymphocyte count
• enlarged liver or spleen
• possibly enlarged lymph nodes
3• elevated lymphocyte count
• low number of red blood cells
• possible enlarged liver, spleen, or lymph nodes
4• elevated lymphocyte count and low platelets
• possible enlarged liver, spleen, or lymph nodes

Binet staging system

The Binet staging system divides CLL into three stages:

Afewer than 3 groups of swollen lymph nodes
B3 or more groups of swollen lymph nodes
Clow levels of red blood cells and platelets

After you receive a diagnosis, your doctor will talk with you about treatment options. Many people with CLL don’t require treatment.

CLL prognostic index

The CLL International Prognostic Index helps doctors determine whether CLL requires treatment. This index uses a point system:

TP53 gene mutated or deleted4 points
unmutated IGHV gene2 points
serum beta-2 microglobulin concentration under 3.5 mg/L2 points
Rai stage 1–4 or Binet stage B–C1 point
age over 65 years1 point

This point system scores you in one of four categories:

CategoryRisk scoreRecommendations
Low risk0–1don’t treat
Intermediate risk2–3don’t treat unless you have many symptoms
High risk4–6treat unless you have no symptoms
Very high risk7–10consider new treatments or clinical trials

iwCLL criteria for treatment

The iwCLL criteria recommend treatment for active disease, meaning you have symptoms such as:

Learn more about CLL treatments.

Here are some frequently asked questions people have about CLL.

What WBC count indicates CLL?

An elevated WBC count can be suggestive of CLL, but you need a flow cytometry test to confirm a diagnosis. Flow cytometry can provide information about B lymphocytes, the type of WBC most pertinent to a CLL diagnosis. Your B lymphocyte count would need to be higher than 5 billion per liter of blood.

What is the life expectancy of someone with CLL?

The 5-year relative survival rate for CLL in the United States is 88%. This means people with CLL live at least 5 years after their diagnosis about 88% as often as people without the cancer.

Is CLL a terminal illness?

CLL is rarely curable, but many people can live for a long time without needing treatment. Most people with CLL do not die from the cancer.

Doctors mainly use the results of blood tests and flow cytometry to diagnose CLL. A CLL diagnosis requires a B lymphocyte count of 5 billion per liter of blood sustained for at least 3 months.

You may also receive other tests, like imaging or a bone marrow biopsy.

Many people with CLL don’t need treatment. Your doctor may recommend treatment if you develop active symptoms, such as a fever or weight loss.