Leukemia - Acute Myeloid - AML: Diagnosis

Approved by the Cancer.Net Editorial Board, 04/2022

ON THIS PAGE: You will find a list of the common tests, procedures, and scans that doctors can use to find out what’s wrong and identify the cause of the problem. Use the menu to see other pages.

How AML is diagnosed

There are many tests used for diagnosing AML. Doctors will also do tests to find out the subtype of AML (see Subtypes). They may also do tests to learn which treatments could work best. Not all tests described here will be used for every person. Your doctor may consider these factors when choosing a diagnostic test:

  • The type of leukemia suspected

  • Your signs and symptoms

  • Your age and general health

  • The results of earlier medical tests

The following tests may be used to diagnose AML:

Blood tests. To diagnose AML, a doctor will do blood tests to count the number of white blood cells and to see if they look abnormal under the microscope. Special lab tests called flow cytometry, or immunophenotyping, and cytochemistry are often used to distinguish AML from other types of leukemia and to determine the exact subtype of AML.

Bone marrow aspiration and biopsy. These 2 procedures are similar and often done at the same time to examine the bone marrow. Bone marrow has both a solid and a liquid part. A bone marrow aspiration removes a sample of the fluid with a needle. A bone marrow biopsy is the removal of a small amount of solid tissue using a needle.

A pathologist then analyzes the sample(s). A pathologist is a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease. A common site for a bone marrow aspiration and biopsy is the pelvic bone, which is located in the lower back by the hip. Doctors generally give a type of medication called anesthesia beforehand to numb the area. Stronger types of anesthesia can also be used to lessen the pain.

If blood tests (see above) indicate AML, it is better to have the bone marrow aspiration and biopsy at the hospital where the patient's cancer treatment will be given so the test does not need to be repeated.

Biomarker testing of the leukemia cells. Your doctor may recommend running laboratory tests to identify specific genes, proteins, and other factors involved in the leukemia. Examining the genes in the leukemia cells is very important because AML can be caused by a buildup of changes (also called mutations) in the cell’s genes. Identifying these changes helps diagnose the specific subtype of AML and choose treatment options. In addition, the results of those tests can also be used to monitor how well treatment is working. Listed below are the more common molecular or genetic tests used for AML.

  • Immunohistochemistry. This test uses a special dye to learn more about leukemia cells and find out the exact subtype of AML. The dye stains cells differently based on the kinds of chemicals in the cells, allowing doctors to determine the type of leukemia cells.

  • Flow cytometry. This test is also called immunophenotyping. Doctors use flow cytometry to measure different characteristics of cancer cells. AML cells have distinctive markers called surface markers. This test distinguishes AML cells from healthy blood cells and from other types of leukemia by identifying these markers.

  • Karotyping or cytogenetics. A karotype is a picture of a person's chromosomes. Chromosomes are found in the nuclei of cells within the body. Chromosomes are long strands of genes made up of DNA. Genes control how cells work by making proteins that have different functions. People usually have 23 pairs of chromosomes. Sometimes, people with cancer have certain changes to their chromosomes. Typically these changes develop during the person's lifetime and were not present at birth.

    One type of change is called a translocation, which happens when a chromosome breaks off and reattaches to another chromosome. Knowing if there are certain translocations can help doctors determine the AML subtype and plan the best treatment. Flourescence-in-situ-hybridization (FISH) is a way to detect chromosome changes in cancer cells and is being used more often to help diagnose and determine the subtype of leukemia. This test is done on tissue removed during a biopsy or aspiration (see above).

    Other types of chromosomal changes that can be present in some subtypes of leukemia include deletions and trisomies. Deletion is when part of a chromosome is missing. Trisomy is when there are extra copies of chromosomes.

Molecular testing. New testing methods have been developed to determine whether there are changes in the leukemia cells that may be helpful to understand how well treatment may work and whether targeted treatments may be an option (see the Types of Treatment section). There are many different types of molecular tests. It is common in AML for the doctor to order a panel of molecular tests that look at dozens of different genes that may be changed in leukemia cells.

Imaging tests. The imaging tests listed below may be used to learn more about the cause of symptoms or to help diagnose infections in patients with AML. They are not regularly used to find out how widespread the AML is because the disease has often spread throughout the bone marrow when it is first diagnosed.

  • Computed tomography (CT or CAT) scan. A CT scan is a test that creates pictures of the inside of the body using x-rays taken from different angles. A computer combines these pictures into a detailed, 3-dimensional image that shows any abnormalities. Sometimes, a special dye called a contrast medium is given before the scan to provide better detail on the image. This dye can be injected into a patient’s vein or given as a pill or liquid to swallow.

  • Magnetic resonance imaging (MRI). An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. A special dye called a contrast medium is given before these scans to create a clearer picture. This dye can be injected into a patient’s vein or given as a pill or liquid to swallow.

  • Positron emission tomography (PET) or PET-CT scan. A PET scan is usually combined with a CT scan (see above), called a PET-CT scan. However, you may hear your doctor refer to this procedure just as a PET scan. A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive sugar substance is injected into the patient’s body. This sugar substance is taken up by cells that use the most energy. Because cancer tends to use energy actively, it absorbs more of the radioactive substance. However, the amount of radiation in the substance is too low to be harmful. A scanner then detects this substance to produce images of the inside of the body. A PET scan may be used to find a myeloid sarcoma (see Introduction) and find out how well treatment is working against the sarcoma.

Lumbar puncture, also called a spinal tap. A lumbar puncture is a procedure in which a needle is used to take a sample of cerebral spinal fluid (CSF) to look at the make up of the fluid and to find out if it contains leukemia cells or blood. CSF is the fluid that flows around the brain and spinal cord. Doctors generally give an anesthetic to numb the lower back before the procedure. The CSF is then examined under the microscope to look for AML cells. This is not a common test for AML.

After diagnostic tests are done, your doctor will review the results with you. If the diagnosis is AML, these results also help the doctor describe the disease. This is called subtyping.

The next section in this guide is Subtypes. It explains the way that doctors describe AML. Use the menu to choose a different section to read in this guide.