CLL
Meaning of CLL: Cells that look mature and behave uselessly accumulate for years, which is why a diagnosis often arrives long before any treatment does.
Definition of CLL
CLL stands for chronic lymphocytic leukemia, a slow-growing cancer in which mature-looking but faulty B lymphocytes build up in the blood, bone marrow and lymph nodes. The cells look almost normal under the microscope yet fail to do the work of an immune cell and refuse to die on schedule. Many cases are found on a blood count taken for another reason.
How does it differ from the other leukemias?
| Leukemia | Cells involved | Usual pace |
|---|---|---|
| Chronic lymphocytic | Mature-looking B lymphocytes | Slow, often measured in years |
| Acute lymphocytic | Immature lymphoid blasts | Fast, treated without delay |
| Chronic myeloid | Maturing myeloid cells | Slow, driven by a single gene fusion |
| Acute myeloid | Immature myeloid blasts | Fast, treated without delay |
The word chronic in a leukemia name refers to the maturity of the cells, not merely to how long the illness runs. Acute lymphocytic leukemia is built of blasts, cells stuck at an early stage. CLL is the opposite case: its cells complete their maturation and then stop working and stop dying, so they pile up gradually. On a blood film they are small and unremarkable, apart from the fragile ones crushed during smearing, described as smudge cells. Diagnosis is usually settled by testing the surface markers on the circulating cells, which identifies a single abnormal population of B cells, so a bone marrow sample is often unnecessary. Chronic myeloid leukemia is slow in the same sense but arises from a different cell family altogether.
Why is treatment often delayed?
Starting treatment in early disease has not been shown to lengthen life, so the usual course is regular monitoring until specific signs of progression appear: falling red cells or platelets, nodes or spleen enlarging steadily, drenching night sweats, weight loss, or a lymphocyte count climbing quickly. Waiting is a plan rather than the absence of one. The disease still causes trouble in the meantime, because the abnormal cells crowd normal antibody production and leave the person prone to infection, and the immune system may turn on its own red cells or platelets and destroy them. Uncommonly the disease changes character and becomes an aggressive lymphoma.
What is small lymphocytic lymphoma?
The same disease under a second name, decided by where the cells have gathered. When they sit mainly in the lymph nodes with few in the blood, it is called small lymphocytic lymphoma; when the blood and marrow carry the bulk of them, it is called leukemia. The cells, the markers and the treatment approach are the same, and the two names describe one condition seen from different angles.
Also known as
Used in a sentence
A routine blood count revealed findings suggestive of CLL, prompting further evaluation.
Good to know
Chronic lymphocytic leukemia and small lymphocytic lymphoma represent the same underlying disease, distinguished mainly by whether the abnormal cells are found predominantly in the blood and marrow or extensively within the lymph nodes.