Diagnosing acute lymphoblastic leukemia (ALL) and your ALL subtype usually involves a series of tests. An accurate diagnosis of the subtype is important. The exact diagnosis helps the doctor
- Estimate how the disease will progress
- Determine the appropriate treatment.
Blood and Bone Marrow Tests
- A bone marrow aspiration removes a liquid marrow sample
- A bone marrow biopsy removes a small amount of bone filled with marrow
Complete Blood Count (CBC) with Differential. 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. The differential measures the numbers of the different types of white blood cells in the sample. People with acute lymphoblastic leukemia (ALL) may have a high number of white blood cells and a low number of red blood cells and platelets.
Blood Chemistry Profile. This is a blood test that measures the levels of certain substances released into the blood by organs and tissues in the body. These substances include electrolytes (such as sodium, potassium and chloride), fats, proteins, glucose (sugar), uric acid and enzymes. Blood chemistry test findings indicate how well a person’s kidneys, liver and other organs are working. These test results, although not used to diagnose leukemia, may show an abnormal amount of a particular substance in the blood that may be a sign of disease or some other health problem. A blood chemistry profile also provides helpful information about any potential organ damage caused by leukemia cells or ALL treatments.
Coagulation Test. This is a blood test that measures how well the blood is able to clot and determines whether there are deficiencies in some proteins, such as fibrinogen.
Cell Assessment. A hematopathologist will examine a sample of blood cells or bone marrow cells under the microscope to determine the size, shape, and type of cells as well as to identify other features of the cells. A significant finding is the appearance of the cells—whether the cells look more like normal, mature blood cells or more like abnormal, immature blood cells (blast cells).
Flow Cytometry. This test is used to classify cells in a blood sample. The classification is based on the types of antigens, or markers/proteins, on the surface of the cells. The pattern of the surface proteins is called the “immunophenotype.” A sample of bone marrow is often used for this test, but a blood sample may also be used. The sample of cells is treated with special manmade antibodies that only stick to the cells if the cells have a specific antigen on them. The cells are then passed through a laser beam. The cells with antibodies attached to them will give off light. Leukemia cells are different from healthy cells; they can have different antigens on their surface depending on whether the cells are myeloid or lymphoid and their stage of development. Flow cytometry helps to confirm an ALL diagnosis. It is also used to determine the type of lymphocytes in which ALL originated and to assess the maturity of the cells. Flow cytometry is also used to check treatment results.
The following tests are used to identify, examine and measure chromosomes and genes.
Cytogenetic Analysis (Karyotyping). In this test a hematopathologist uses a microscope to examine the chromosomes inside of cells. Karyotyping is used to look for abnormal changes in the chromosomes of the leukemia cells of patients with ALL.
Cytogenetic testing is done using either a bone marrow or a blood sample. The leukemia cells in the sample are allowed to grow in the laboratory and then they are stained prior to examination. The stained sample is examined under a microscope and then photographed to show the arrangement of the chromosomes (the karyotype). The karyotype will show if there are any abnormal changes in the size, shape, structure or number of chromosomes in the leukemia cells.
Cytogenetic analysis provides information that is important when determining a patient’s treatment options and prognosis. This information can 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.
Fluorescence in situ Hybridization (FISH). This is a cytogenetic laboratory technique that is used to identify and examine genes or chromosomes in cells and tissues. In cases of ALL, doctors use FISH to detect certain abnormal changes in the chromosomes and genes of leukemia cells.
Polymerase Chain Reaction (PCR). A PCR is a very sensitive laboratory technique that is used to detect and measure some genetic mutations and chromosomal changes that are too small to be seen with a microscope. Polymerase chain reaction testing essentially increases or “amplifies” small amounts of specific pieces of either RNA (ribonucleic acid) or DNA to make them easier to detect and measure. This test can find a single leukemia cell among more than 500,000 to one million normal cells. Polymerase chain reaction testing is one method used to determine the amount of minimal residual disease (MRD), the small amount of cancer cells left in the body after treatment. This testing can be done on a bone marrow or a blood sample.
Spinal Fluid Test
The following test examines the fluid in the spinal column for ALL cells.
Lumbar Puncture. Acute lymphoblastic leukemia can spread to the cerebrospinal fluid (CSF), the fluid that flows around the brain and spinal cord. In order to determine whether or not leukemia cells have spread to this area, a sample of the CSF is tested. A lumbar puncture (also called a “spinal tap”) is a procedure that is used to collect the CSF from the spinal column. After the area over the spine in the lower part of the back has been numbed with a local anesthetic, a thin needle is inserted between two bones (vertebrae) and into the CSF. A sample of the fluid is withdrawn and examined under a microscope to look for leukemia cells that may have spread to the brain and spinal cord.
These tests create images of the inside of the body.
Computed Tomography (CT) Scan. At times, leukemia may grow outside the bone marrow—most commonly in lymph nodes. A CT scan may be used to look for enlarged lymph nodes, liver or spleen caused by an accumulation of leukemia cells in the chest, abdomen and pelvis.
Magnetic Resonance Imaging (MRI) Scan. An MRI scan of the head and/or spinal cord should be done if a patient has symptoms (such as headache or seizures) that suggest that ALL cells may have spread to the brain and spinal cord.
Ultrasonography. This procedure uses high-energy sound waves to examine tissues and organs inside the body. Testicular involvement can occur so an ultrasound examination of the scrotum (the external sac that contains the testicles) may be needed to see if a mass is present.
Echocardiogram. A computerized image of the heart is created by bouncing sound waves (ultrasound) off internal tissues or organs of the chest. An echocardiogram shows the heart’s size, shape and position as well as its internal structures. It also shows how the heart is beating and how it is pumping blood. Some treatments for ALL can damage the heart so the doctor may want to evaluate a patient’s heart and cardiac function in order to plan the best treatment.
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 blast of lymphoid origin (lymphoblasts) in the bone marrow samples
- 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 done during or after treatment to see how your ALL cells are responding to therapy.
Click here for the steps involved with a new diagnosis of acute leukemia.
Newly Diagnosed Checklist
The College of American Pathologists (CAP) and the American Society of Hematology (ASH) provide practical guidance for patients and caregivers coping with a new diagnosis of acute leukemia. This checklist will help ensure that you receive the best treatment for your unique situation: Click Here
- Download or order The Leukemia & Lymphoma Society's free booklet, Acute Lymphoblastic Leukemia.
- Blood Tests
- Understanding Blood Counts
- Bone Marrow Tests
- Questions and Answers for Patients With Acute Leukemia