Acute lymphoblastic leukemia (ALL)

by Jason Wasserman MD PhD FRCPC and Aleksandra Paliga MD FRCPC
May 2, 2024

Acute lymphoblastic leukemia (ALL) is a type of cancer that affects the blood and bone marrow. It is characterized by the rapid growth of immature white blood cells (WBCs), known as lymphoblasts or leukemic blasts, which crowd out normal cells, impairing the bone marrow’s ability to produce healthy blood cells. This type of cancer is commonly diagnosed in children, although it can also occur in adults. When this type of cancer arises outside of the bone marrow and blood, it is called lymphoblastic lymphoma.

What are the most common types of acute lymphoblastic leukemia?

Acute lymphoblastic leukemia can be classified based on the type of lymphocytes affected. The most common types are:

• B-cell acute lymphoblastic leukemia (B-ALL): This subtype originates from immature B lymphocytes and is the most common form, especially in children.
• T-cell acute lymphoblastic leukemia (T-ALL): Originating from immature T lymphocytes, this subtype is less common and tends to occur more often in older children and adolescents.

Who gets acute lymphoblastic leukemia?

Acute lymphoblastic leukemia is most commonly diagnosed in children between the ages of 2 and 5 years. However, there is another peak in incidence in older adults over 50 years of age. The disease affects males slightly more often than females and is more common among certain ethnic groups, such as Hispanics and whites.

Symptoms of acute lymphoblastic leukemia

Symptoms of acute lymphoblastic leukemia result from the suppression of normal bone marrow function due to the overproduction of lymphoblasts, which include:

• Fatigue and weakness due to anemia.
• Fever and infections due to neutropenia (low levels of neutrophils, a type of white blood cell).
• Bleeding or bruising easily due to thrombocytopenia (low platelet counts).
• Bone and joint pain.
• Swollen lymph nodes, liver, or spleen.
• Unintended weight loss

What causes acute lymphoblastic leukemia?

The exact causes of acute lymphoblastic leukemia are not completely understood, but several factors are believed to contribute to its development:

• Genetic factors: Certain genetic conditions, such as Down syndrome, are associated with an increased risk of developing this type of cancer.
• Environmental exposures: Previous chemotherapy, radiation exposure, and possibly other environmental toxins have been implicated.
• Random genetic mutations: Many cases of acute lymphoblastic leukemia involve mutations in the DNA of bone marrow cells, which occur randomly and are not inherited.

Learn more about your pathology report:

B-cell acute lymphoblastic leukemia (B-ALL)

T-cell acute lymphoblastic leukemia (T-ALL)

About this article

This article was written by doctors to help you read and understand your pathology report. Contact us if you have any questions about this article or your pathology report. Read this article for a more general introduction to the parts of a typical pathology report.

Other helpful resources

Atlas of Pathology