The symptoms for acute myelogenous leukemia (AML) are similar to those of other blood diseases. An accurate diagnosis requires a thorough physical examination, a complete medical history and several diagnostic tests. The tests may include the following.
Complete Blood Count (CBC)
This test examines blood for the number of red blood cells, white blood cells and platelets, and the amount of hemoglobin (protein that carries oxygen) in your red blood cells. Essentially all patients with AML will have an abnormality in their CBC.
Peripheral Blood Smear
A blood sample is examined for the number and types of white blood cells, the presence of blasts (leukemia cells) and any changes in the shape of your blood cells. If more than 20 percent of the cells examined are blasts, the diagnosis is very likely to be AML.
Blood Chemistry Tests
These tests measure the levels of certain substances in your body to determine whether your organs are functioning properly.
Flow Cytometry and Immunophenotyping
Flow cytometry helps determine what types of cells are in a blood or bone-marrow sample. The sample is treated with special antibodies (immune system–related proteins) that attach to certain substances on the cell surface. When these cells, with attached antibodies, are passed by a laser beam, they give off light. A computer then analyzes and sorts the cells. Flow cytometry allows physicians to determine whether an increased white blood cell count is due to a reactive process such as fighting off infection or to cancer. By examining the types of antigens (markers) on the cell surface, the type of cell can be identified. Immunophenotyping can also help to distinguish AML from another form of leukemia or lymphoma.
Bone Marrow Aspiration and Biopsy
A sample of bone marrow, blood and a small piece of bone are taken from the hip bone using a hollow syringe. The cells are then examined under a microscope to see if leukemic cells are present. While this short procedure can cause some pain, it provides valuable information about the bone marrow and blood cells. Typically, it is essential to the diagnosis of AML. This test is used to see how far the AML has progressed or later to see how well treatment is working.
Blood or bone-marrow cells are examined under a microscope for changes in the chromosomes (long strands of DNA). Sometimes a chromosome is missing a part or has attached to another chromosome (translocation), which makes the cell behave abnormally. Different patients have different chromosome patterns, and the type of pattern often predicts how well the disease will respond to standard therapy. If the chromosome pattern predicts a poor response to standard therapy, physicians may recommend the patient receives investigational therapy in a clinical study.
Fluorescent in Situ Hybridization (FISH)
The fluorescent dyes used in this test attach to specific parts of certain chromosomes. More chromosomal abnormalities can be seen under a microscope using this technique than with the standard technique described above. The information obtained from the FISH analysis may help to distinguish AML from other forms of leukemia or lymphoma.
Even with the use of FISH, many patients will still appear to have normal chromosomes. Recently the use of sophisticated tests has revealed that many such patients will have subtle genetic abnormalities. These often have great prognostic significance. For example, patients who seem to have normal chromosomes but who have an abnormality in the gene for FLT3 have much worse outcomes with standard treatment than patients with normal chromosomes who do not have an FLT3 abnormality.
A new diagnostic tool called OncoPlex may make a difference in the treatments and outcomes of many SCCA patients. Developed by researchers at UWMedicine, OncoPlex tests each patient’s actual tumor tissue for the presence of characteristic genetic abnormalities called driver mutations. Each driver mutation causes tumors that behave differently on the molecular level and, thus, have different vulnerabilities. The OncoPlex panel studies only genes with characteristic mutations known to cause cancer variants, and for which a therapy is available. The OncoPlex report includes both data and a detailed interpretative section to help oncologists make and support their diagnoses.
Chemical stains are applied to a sample of blood. The stains react with certain types of leukemia cells, so they can be seen more clearly under a microscope. Cytochemistry may be used to distinguish AML from acute lymphocytic leukemia (ALL) or other blood diseases.
Reverse Transcriptase–Polymerase Chain Reaction (RT-PCR)
RT-PCR is a very sensitive DNA replication technique that can be used to detect changes in the structure or function of genes. This test is used to diagnose acute promyelocytic leukemia (APL), subtype M3.
A small needle is advanced into the spinal cavity in the lower back, and a small amount of cerebral spinal fluid (CSF) is withdrawn. The CSF is then examined for abnormal blood cells to determine whether the cancer has spread to the spinal fluid.
Imaging tests such as chest X-ray, CT scan, MRI or ultrasound exam may be performed to determine whether the leukemia has spread to other parts of your body.