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Diagnosing acute lymphoblastic leukemia (ALL) and your ALL subtype usually involves a series of tests. An accurate diagnosis of your subtype is important. The exact diagnosis helps your doctor estimate how the disease will progress and determine the appropriate treatment.
The information on this page covers how ALL is diagnosed in adults. Visit Childhood ALL to learn about signs and symptoms, diagnosis, and treatment information for children with ALL.
Tests your doctor may use to diagnose ALL
Your doctor may use the following tests to diagnosed ALL:
Blood and bone marrow tests
Blood tests measure the number of red and white blood cells and platelets in the blood; bone marrow tests measure the fluid and tissue in your marrow. Open each section below to learn more.
This test is used to measure the number of red blood cells, white blood cells, and platelets in a sample of blood. It measures the amount of hemoglobin in the red blood cells. The CBC should include a differential, which measures the numbers of the different types of white blood cells in the sample. People with ALL often have lower-than-normal numbers of red blood cells and platelets and may have higher-than-normal or lower-than-normal white blood cell counts.
If the CBC findings suggest leukemia, a diagnosis of ALL can sometimes be confirmed with additional testing of the blood sample. Sometimes, however, an ALL diagnosis can be made only after the examination of a sample of bone marrow cells.
These two procedures are generally done at the same time in a doctor's office or a hospital. For both procedures, the patient is given general anesthesia or medication to numb the area. The samples are usually taken from the hip bone using special needles.
- A bone marrow aspiration removes a liquid marrow sample
- A bone marrow biopsy removes a small amount of bone filled with marrow
Learn more about bone marrow tests.
View the interactive 3D model to help you visualize and better understand the procedure. Click or tap the "Interact in 3D" button to begin.
Biomarker testing
These laboratory tests check for changes in the proteins, genes, and chromosomes of the cancer cells. Each person's cancer has a unique pattern of biomarkers. Biomarker testing is used to help determine the subtype of ALL and plan treatment. Open each section below to learn more.
This test is used to identify cells based on the types of proteins on the cell surfaces. It can help determine whether a person has B-cell ALL or T-cell ALL and the subtype of ALL. This test can also be used to see if there are any residual cancer cells remaining in the body after treatment called measurable residual disease (MRD).
Each cell in the body has chromosomes that carry genes. Genes contain instructions that tell each cell what to do. Cytogenetic analysis is used to look for abnormal changes in the chromosomes of leukemia cells. The results of this test help your doctor identify your ALL subtype and plan your treatment.
This information can also predict how the disease will respond to therapy. For example, a translocation between chromosomes 9 and 22 is associated with a diagnosis of Philadelphia chromosome-positive (Ph+) ALL, a subtype of ALL that is treated differently than other subtypes.
This test is used to look at the genes or chromosomes in cells and tissues. Doctors use this test to find changes in chromosomes and genes in the leukemia cells.
This test finds and measures some genetic mutations and chromosome changes that are too small to be seen, even with a microscope. PCR is also used to test for MRD.
This test looks for mutations in the genes of ALL cells. Certain mutations are markers that can help doctors identify a patient’s ALL subtype and predict how the disease will progress. Next-generation sequencing is also used to test for MRD.
Diagnosing ALL
After your doctor takes samples of your blood and bone marrow, a hematopathologist confirms a diagnosis and identifies the ALL subtype. A hematopathologist is a specialist who studies blood cell diseases by looking at samples of blood and marrow cells and other tissues.
The diagnosis of ALL is confirmed by identifying leukemic blasts of lymphoid origin (lymphoblasts) in the bone marrow samples; and determining the percentage of blast cells in the bone marrow.
Typically, there are no blast cells in the blood and no more than 5 percent of the cells in the bone marrow are blast cells. In ALL, at least 20 percent of the cells in the bone marrow are lymphoblasts.
If you're diagnosed with ALL, blood and bone marrow tests are also administered during or after treatment to see how the ALL cells are responding to therapy.
Newly diagnosed checklist
This infographic from the College of American Pathologists (CAP) and the American Society of Hematology (ASH) provides practical guidance for patients and caregivers coping with a new diagnosis of an acute leukemia. It will help ensure that you receive the best treatment for your unique situation.
Diagnosing ALL subtypes
Doctors classify ALL into subtypes by using various tests. It's important to get an accurate diagnosis since your subtype plays a large part in deciding the type of treatment you'll receive.
Depending on your ALL subtype, the doctor will determine:
- The type of drug combination needed for your treatment
- The length of time you'll need to be in treatment
- Other types of treatment that may be needed to achieve the best outcomes
Leukemia cells can be classified by the unique set of proteins found on their surface. These unique sets of proteins are known as “immunophenotypes.” Based on immunophenotyping of the leukemia cell, the World Health Organization (WHO) classifies ALL into two main subtypes.
- B-cell lymphoblastic leukemia/lymphoma: This subtype begins in immature cells that would normally develop into B-cell lymphocytes. This is the most common ALL subtype. Among adults, B-cell lineage represents 75 percent of cases.
- T-cell lymphoblastic leukemia: This subtype of ALL originates in immature cells that would normally develop into T-cell lymphocytes. This subtype is less common, and it occurs more often in adults than in children. Among adults, T-cell lineage represents about 25 percent of cases.
Genetic changes
In addition to classifying ALL as either B-cell or T-cell, it is further classified based on certain changes to the chromosomes and genes found in the leukemia cells. This identification of specific genetic abnormalities is critical for disease evaluation, risk stratification, and treatment planning.
Translocations are the most common type of genetic change associated with ALL. In a translocation, the DNA from one chromosome breaks off and becomes attached to a different chromosome. Sometimes pieces from two different chromosomes trade places. A translocation may result in a “fusion gene,” an abnormal gene that is formed when two different genes are fused together.
Another type of genetic change that occurs in ALL is the result of numerical abnormalities. A numerical abnormality is either a gain or loss in the number of chromosomes from the normal 46 chromosomes. A change in the number of chromosomes can affect the growth, development, and functioning of body systems.
About 75 percent of adult ALL cases can be classified into subgroups based on chromosomal abnormalities and genetic mutations. Not all patients have the same genetic changes. Some changes are more common than others, and some have a greater effect on a patient’s prognosis.
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