Leukemia - Acute Myeloid - AML: Diagnosis

Approved by the Cancer.Net Editorial Board, 06/2017

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.

Doctors use many tests to find, or diagnose leukemia. They also do tests to find out the subtype (see Subtypes). Doctors may also do tests to learn which treatments could work best. For example, imaging tests can show more information about the cause of your symptoms. Imaging tests show pictures of the inside of the body.

For most types of cancer, a biopsy is the only sure way for the doctor to know whether an area of the body has cancer. In a biopsy, the doctor takes a small sample of tissue for testing in a laboratory. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis.

This list describes options for diagnosing AML. Not all tests listed below 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 medical condition

  • 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 tests called flow cytometry, or immunophenotyping, and cytochemistry are sometimes 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. The skin in that area is numbed with medication beforehand. Other types of anesthesia (medication to block the awareness of pain) may also be used. If blood tests (see above) indicate AML, it is better to have the bone marrow aspiration and biopsy at the hospital where treatment will be given so the test does not need to be repeated.

  • Molecular and genetic testing. 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 important because AML can be caused by a buildup of mistakes (also called mutations) in the cell’s genes. Identifying these mistakes 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.

    • Cytochemical and immunohistochemical tests are laboratory tests that are used to find out the exact subtype of AML. In cytochemical tests, a special dye is used that stains the different types of leukemia cells differently based on the chemicals in the cells. For AML, immunohistochemical tests and a test called flow cytometry are used to find markers on the surface of the leukemia cells. The different subtypes of leukemia have different and unique combinations of cell surface markers.

    • Cytogenetics is a way to look at a cell’s chromosomes (long strands of genes) through a microscope to analyze the number, size, shape, and the arrangement of the chromosomes to find genetic changes in the leukemia cells. Sometimes, a chromosome breaks off and reattaches to another chromosome, which is called a translocation. Other times, part of a chromosome is missing, called a deletion. A chromosome can also be made more than once, most often called a trisomy. Some subtypes of leukemia are caused by chromosome translocations, deletions, or trisomies.

      Knowing if there are certain translocations may 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).

    • The molecular genetics of leukemia cells can also be used to help find out if a person needs more or less chemotherapy and/or bone marrow/stem cell transplantation (see the Treatment Options section). The goal of this type of testing is to look for very small genetic mutations, called sub-microscopic mutations.

  • 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.

    • A computed tomography (CT or CAT) scan is a test that creates a 3-dimensional picture of the inside of the body using x-rays taken from different angles. A computer combines these images into a detailed, cross-sectional view 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 to swallow.

    • A magnetic resonance imaging (MRI) is a test that 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 to swallow.

    • 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. 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 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 doctor uses a needle to take a sample of cerebral spinal fluid (CSF) to look at the make up of the fluid and to find out is 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. Patients with AML do not often need to have a lumbar puncture.

After diagnostic tests are done, your doctor will review all of 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. You may use the menu to choose a different section to read in this guide.