Acute myeloid leukemia (AML) is a rare type of blood cancer that affects bone marrow and white blood cells. AML is a fast-growing, or acute, form of leukemia, which doctors diagnose using blood and bone marrow tests.
This article explains AML and its connection with bone marrow. Learn more about what to expect if a doctor prescribes a bone marrow biopsy and when it might be necessary.
Blood cells are made in a person’s bone marrow. The National Cancer Institute (NCI) Dictionary of Cancer Terms defines
The Leukemia and Lymphoma Society’s (LLS) booklet, Acute Myeloid Leukemia in Adults, explains that these stem cells develop into two main types: lymphoid and myeloid. AML affects the development of myeloid cells.
According to the LLS fact sheet, these atypical cells keep growing and dividing at such a rate that they build up in the bone marrow. Over time, the bone marrow gets overwhelmed by the atypical cells and slows down or stops producing healthy blood cells.
The NCI Dictionary of Cancer Terms defines a
According to the LLS, this procedure may be carried out in a doctor’s office or at a hospital. After numbing the skin and surface of the bone with a local anesthetic, the doctor inserts a wide needle into the bone and rotates it to collect the sample.
The LLS notes that some people find the test uncomfortable and others may experience bone pain in the days following the test.
Doctors usually collect a sample of the liquid inside the bone marrow at the same time. This test is called bone marrow aspiration. A thinner, hollow needle is inserted into the marrow to collect some fluid. Scientists then examine the samples under a microscope.
When diagnosing AML, doctors look at the shape, size, and appearance of any atypical cells. The LLS booklet Acute Myeloid Leukemia in Adults explains that a healthy person should not have any atypical cells in their blood and fewer than 5% in their bone marrow.
Doctors confirm the diagnosis of AML if more than 20% of cells have atypical characteristics in an individual’s blood or bone marrow.
The biopsy results also help determine the subtype of AML. The LLS explains how the World Health Organization (WHO) looks at genetic mutations and irregularities in the chromosomes to determine this. These differences can impact how a person responds to different treatments.
After initial treatment
The National Comprehensive Cancer Network’s (NCCN) Guidelines for Patients: Acute Myeloid Leukemia highlights that another bone marrow biopsy will be necessary to show the effectiveness of the initial treatment.
The NCCN explains that the timing of this test depends on the subtype, but it is typically within 2–3 weeks of the first round of treatment.
If the leukemia returns, doctors call this a relapse. The NCCN guidelines explain that after treatment, a person with AML will need regular blood tests to check for atypical cells.
If atypical cells are present, another bone marrow biopsy may be needed.
Blood tests are another important part of the diagnostic process for AML.
Researchers from a
However, they conclude that bone marrow biopsies are an essential tool for diagnosing AML in the first place and evaluating any potential relapse.
The LLS explains what medical experts are looking for in the different tests carried out on the sample.
Immunophenotyping or flow cytometry tests help identify the subtype of AML. Cells for this test are colored with a light-sensitive dye before being passed through a laser beam. Any cells with specific antibody markers change color during the test and can be counted.
Molecular tests look at the genes and chromosomes in the atypical AML cells. The
- Cytogenetics. This test looks at the chromosomes under a microscope to identify any missing or unusual parts.
- Fluorescent in situ hybridization (FISH). This test can pick up changes that may not be noticeable with cytogenetic testing.
- Polymerase chain reaction (PCR). This very sensitive test can pick up small numbers of leukemia cells.
According to the NCCN guidelines, PCR tests can find a single leukemia cell among 100,000 normal cells.
Bone marrow biopsies are important tests for diagnosing and monitoring people with AML. Healthcare professionals collect samples to test for chromosomal changes to the cells and help doctors plan treatment options.
By taking a bone marrow sample, doctors can identify which subtype of AML a person has and prescribe the most effective treatment available for it.
During the procedure, doctors numb the skin outside the bone with an anesthetic. They usually take samples from the hip bone. A person may notice discomfort during the procedure and some pain in the following days.