Diagnosis

In the past, many people with chronic lymphocytic leukemia (CLL) were diagnosed after symptoms developed. Today, most cases are identified earlier—often through routine blood tests during an annual physical or follow-up for another condition.

An initial sign of CLL is an elevated lymphocyte count (a type of white blood cell). Because other conditions can also cause increased lymphocytes, additional testing is needed to confirm the diagnosis.

Confirming a Diagnosis

CLL is typically confirmed using a blood test called flow cytometry, which examines proteins on the surface of cells. A diagnosis is made when a characteristic pattern of markers is present, including CD5, CD19, CD20, and CD23.

These tests are usually reviewed by a hematopathologist with expertise in blood cancers.

Staging and Evaluation

Once CLL is diagnosed, doctors assess the extent of the disease. This may include:

• Physical examination of lymph nodes, liver, and spleen
• Blood tests to evaluate overall health and blood cell levels
• Imaging (such as CT scans), if clinically indicated

A bone marrow biopsy is not always required for diagnosis but may be helpful in certain cases to better understand disease status or guide treatment decisions.

Prevalence and Outlook

CLL is one of the most common types of leukemia in adults in the United States. Due to earlier detection and advances in treatment, many people live with CLL for years or even decades.

Ongoing improvements in diagnosis and therapy continue to extend survival and improve quality of life for patients.