Blood cell development. A blood stem cell goes through several steps to become a red blood cell, platelet, or white blood cell.
In ALL, too many stem cells develop into lymphoblasts and do not mature to become lymphocytes. These lymphoblasts are called leukemia cells. The leukemia cells do not work like normal lymphocytes and are not able to fight infection very well. Also, as the number of leukemia cells increases in the blood and bone marrow, there is less room for healthy white blood cells, red blood cells, and platelets. This may lead to infection, anemia, and easy bleeding.
This summary is about acute lymphoblastic leukemia. See the following PDQ summaries for information on other types of leukemia:
See the Childhood Acute Lymphoblastic Leukemia Subgroups section for more information.
Family history and exposure to radiation may affect the risk of developing childhood ALL.
Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. People who think they may be at risk should discuss this with their doctor. Possible risk factors for ALL include the following:
Tests that examine the blood and bone marrow are
used to detect (find) and diagnose childhood ALL.
The following tests and procedures may be used:
Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient's health habits and past illnesses and treatments will also be taken.
Complete blood count (CBC) with differential: A procedure in which a sample of blood is drawn and checked for the following:
Complete blood count (CBC). Blood is collected by inserting a needle into a vein and allowing the blood to flow into a tube. The blood sample is sent to the laboratory and the red blood cells, white blood cells, and platelets are counted. The CBC is used to test for, diagnose, and monitor many different conditions.
Bone marrow aspiration and biopsy. After a small area of skin is numbed, a Jamshidi needle (a long, hollow needle) is inserted into the patient’s hip bone. Samples of blood, bone, and bone marrow are removed for examination under a microscope.
Cytogenetic analysis: A laboratory test in which the cells in a sample of blood or bone marrow are viewed under a microscope to look for certain changes in the chromosomes in the lymphocytes. For example, in Philadelphia chromosome-positive ALL, part of one chromosome is moved to another chromosome. This is called the “Philadelphia chromosome.” Other tests, such as fluorescence in situ hybridization (FISH), may also be done to look for certain changes in the chromosomes.
Philadelphia chromosome. A piece of chromosome 9 and a piece of chromosome 22 break off and trade places. The bcr-abl gene is formed on chromosome 22 where the piece of chromosome 9 attaches. The changed chromosome 22 is called the Philadelphia chromosome.
Immunophenotyping: A test in which the cells in a sample of blood or bone marrow are looked at under a microscope to find out if malignant lymphocytes (cancer) began from the B lymphocytes or the T lymphocytes.
Blood chemistry studies: A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease in the organ or tissue that makes it.
Chest x-ray: An x-ray of the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
Certain factors affect prognosis (chance of recovery) and treatment options.