Chronic lymphocytic leukemia (CLL) is a type of cancer affecting the bone marrow lymphocytes. It can affect B or T cells and may be slow- or fast-growing.
It affects lymphocytes, a type of white blood cells that play a significant role in the immune system.
There are two kinds of lymphocytes: B cells and T cells. CLL can affect either type. Experts can classify CLL depending on the cells it affects and whether it is fast- or slow-growing.
This article discusses the types of CLL, their causes and symptoms, and more.
B cells are a specific type of lymphocytes responsible for making antibodies that help fight bacteria and viruses.
CLL occurs when cancerous B cells are present in the bone marrow and bloodstream. When the cancer cells are mainly present in the lymph nodes, the disease is called small lymphocytic leukemia instead of CLL.
About 95% of people with CLL have B-cell CLL.
Some people with B-cell CLL remain stable for years, with the disease having no impact on their overall health and lifestyle.
B-cell prolymphocytic leukemia (PLL)
B-cell PLL is a very rare and aggressive form of B-cell CLL. In people with B-cell PLL, immature lymphocytes called prolymphocytes are present in the blood. It often occurs as a transformation of B-cell CLL, but it may also happen by itself.
T cells are lymphocytes that play a significant role in adaptive immunity. They help B cells make more antibodies and destroy infected host cells, foreign invaders, and cancer cells. T cells also produce cytokines, which help activate other parts of the immune system.
T-cell CLL or T-cell PLL is a
It is more aggressive and has a less favorable outlook than B-cell CLL. The median survival for the condition is 1 year.
People often have widespread disease upon diagnosis, with the cancer cells already present in the blood, bone marrow, skin, and other organs.
CLL can be either indolent, which means it is slow-growing, or aggressive, which means it is fast-growing. People with an indolent form have an increased number of lymphocytes in the blood, but other blood cell counts remain normal or just slightly below average.
People with indolent CLL may not need treatment until symptoms appear. Many live for years without experiencing any problems.
One-third of those with CLL have an indolent form. They have a similar life expectancy to people of the same age who do not have CLL. Others may have no symptoms for 5–10 years before the disease rapidly progresses.
In about 10% of people with CLL, the cancer is aggressive, or fast-growing. Aggressive CLL grows quickly and leaves little room for healthy blood cells.
Without treatment, a person with aggressive CLL may develop symptoms and complications. Some people may need blood or platelet transfusions even before receiving a CLL diagnosis.
People with this form of CLL have a median survival rate of 1–3 years from diagnosis.
Determining a person’s immunoglobulin heavy chain variable region gene (IGHV) mutation status helps experts identify whether a person has an aggressive CLL. IGHV also helps determine a person’s prognosis and response to treatment.
People with mutated IGHV typically have a less aggressive disease than those with unmutated IGHV.
About 50–75% of people with CLL do not have symptoms upon diagnosis. Doctors often discover it during routine blood tests or exams.
Symptoms tend to be similar regardless of which cells the leukemia affects or whether CLL is IG-mutated or IG-unmutated. However, IG-unmutated CLL progresses sooner and causes more symptoms earlier than IG-mutated CLL.
When symptoms develop, they may include:
- painless swelling of lymph nodes (lymphadenopathy)
- tiredness and weakness
- fever and infections
- pain or a feeling of fullness below the ribs (splenomegaly)
- easy bruising or bleeding
- small, pinpoint round spots on the skin (petechiae)
- unexplained weight loss
- drenching night sweats
- loss of appetite
Learn more about chronic lymphocytic leukemia.
The course and outlook of CLL are highly variable. Some people remain symptom-free for decades. Others develop symptoms rapidly and need treatment soon after diagnosis.
- are male
- are aged 65 or older
- have other medical conditions
- have specific CLL characteristics, such as unmutated IGHV
- have a high lymphocyte count (>50,000)
- already have advanced CLL at the time of diagnosis
Conditions that have similar symptoms to CLL include:
CLL affects lymphocytes in the bone marrow. It can affect B cells or T cells.
It has a varied course and can be slow- or fast-growing. Many people live for decades without symptoms, while others develop symptoms rapidly and require treatment soon after diagnosis.
The outlook for CLL depends on various factors, including age, other medical conditions, and certain characteristics of the cancer cells.