Chronic Lymphocytic Leukemia (CLL)

Blood smear showing a
marked lymphocytosis
characteristic of CLL

Chronic lymphocytic leukemia (CLL) is a B-cell disorder in which white blood cells (B-lymphocytes) live longer than normal and accumulate in the blood and bone marrow and sometimes the lymph nodes. This accumulation of white blood cells crowds out healthy lymphocytes and causes immune system problems.

CLL is closely related to small lymphocytic lymphoma (SLL); in fact, many oncologists consider them the same disease. CLL is the second most common type of leukemia.


CLL is a slow-progressing or indolent disease with a median survival rate of 10 years. The disease is frequently asymptomatic in the early stages but if present, symptoms include:

  • Enlarged, but painless, lymph nodes
  • Fatigue
  • Fever
  • Night sweats
  • Weight loss
  • Frequent infections

Causes of CLL

CLL is the result of a genetic mutation that results in the production of white blood cells that live too long and become too large. Beyond this understanding there is no known direct cause of CLL.


CLL can be diagnosed through a series of tests, beginning with a blood count. An abnormally high white cell count will lead to further testing to determine the type of lymphocytes involved and the nature of the abnormality. Flow cytometry, genetic testing and bone marrow tests may all be involved depending on the difficulty of diagnosis and severity of the disease.

Once the diagnosis is complete, it can be determined whether the CLL is at an early, intermediate or advanced stage.


Early stage CLL may not be treated initially as the side effects of treatment may be worse than the symptoms of the disease. This "watch and wait" therapy does not decrease chances for survival or diminish the efficacy of future treatments.

More advanced stages of CLL may be treated with chemotherapy, bone marrow or stem cell transplants, or combination therapy involving targeted drugs such as Treanda® and Rituxan®.

Related Reading

LymphomaInfo Social