Diagnosis

Doctors use many tests to diagnose leukemia. Some tests may also determine which treatments may be the most effective. Your child’s doctor may consider these factors when choosing a diagnostic test:

• Age and medical condition
  
  
• The type of cancer suspected
  
  
• Severity of symptoms
  
  
• Previous test results

When a child has signs and symptoms of leukemia, the doctor will ask about the child’s medical history and perform a physical examination. In addition, the following tests may be used to diagnose AML:

Blood tests. Complete blood count (CBC) and cell type (differential count) are blood tests done to count the number of each type of blood cell under a microscope and to determine if they look abnormal.

Bone marrow aspiration and biopsy. A bone marrow aspiration is performed if the blood test shows abnormal blood counts. For this test, after sedation, the child’s skin is numbed with a local anesthetic and a needle is inserted into a bone in the hip until it reaches the bone marrow. A small amount of bone marrow is removed and examined under a microscope. This is called an aspirate. Your child’s doctor may also use a hollow needle in the same location to withdraw a solid core of bone marrow. This is called a biopsy. This will help the doctor determine if and what type of leukemia is present.

Cytochemical and immunohistochemical tests. Cytochemical and immunohistochemical tests are laboratory tests that are used to determine the exact subtype of AML (see Subtypes). In cytochemical tests, a special dye is used that stains the different types of leukemia cells differently based on the chemical contents of the cells. Immunohistochemical tests for AML are used to identify markers on the surface of the leukemia cells. The different subtypes of leukemia have different and unique combinations of cell surface markers.

Cytogenetics/genetic testing. Cytogenetics is the analysis of a cell’s chromosomes, including the number, size, shape, and the arrangement of the chromosomes. This examination may be used to identify genetic changes in the leukemia cells. Sometimes, a chromosome (a long strand of genes) breaks off and reattaches to another chromosome (called a translocation). Other times, part of a chromosome is missing (called a deletion) or sometimes a chromosome is produced more than once (most often called a trisomy). Some subtypes of leukemia are caused by chromosome translocations, deletions, or trisomies. Knowing if certain translocations are present may help doctors classify the AML subtype and plan the best treatment. Flourescence-in-situ-hybridization (FISH) is a powerful way of detecting chromosome changes in cancer cells and is increasingly used in the diagnosis and subtyping of leukemia.

Molecular genetic signatures of leukemia cells can also be used to help identify if a person needs more or less chemotherapy and/or stem cell transplantation. People with the Flt3 (pronounced flit 3) genetic mutation, called internal tandem duplication (ITD), and specifically, those with a high allelic ratio ITD mutation have a high risk that the cancer will come back after treatment. For these children and adults, the use of stem cell transplantation may improve survival when used after the first complete remission (see Treatment).

New tests are being developed to study other genetic changes that may be present but cannot be seen in the routine examination of chromosomes. These genetic tests will be done using a sample of the child’s blood or bone marrow.

To learn more about what to expect during common diagnostic tests, read Cancer.Net: Tests and Procedures.

To learn about the terms used in this section, read the Cancer.Net Feature: Cancer Terms to Know: Newly Diagnosed.