Diagnosis of Childhood Acute Myeloid Leukemia

Executive Summary

Several diagnostic tests helps in determining childhood acute myeloid leukemia. The main procedures to diagnose childhood acute myeloid leukaemia are a patient’s medical history, complete blood cell count, physical examination, and bone marrow aspiration. Hence, the common diagnostic tests for childhood acute myeloid leukaemia include blood tests, bone marrow aspiration and biopsy, and molecular and genetic testing to identify specific genes, proteins, and other factors involved in leukaemia (Cytochemical and immunohistochemical tests, Cytogenetics, Fluorescence-in-situ-hybridization (FISH)), molecular genetics, and whole-genome testing.

Diagnosis of Childhood Acute Myeloid Leukemia

Many tests helps to diagnose cancer. They also do tests to see if cancer has spread to another part of the body from where it began. So, if this happens, it is metastasis. For instance, imaging tests can represent if cancer has spread. Imaging tests show pictures of the body from the inside. Doctors can also do tests to learn which treatments would work best.

A biopsy is the sure short way for the doctor to know if an area of the body has cancer for most types of cancer. In a biopsy, the doctor takes a small tissue sample for testing in a laboratory. So, the doctor may suggest other tests if a biopsy cannot help diagnose.

The doctor may consider given factors when choosing a diagnostic test:

• Your signs and symptoms
• The age and general health status
• The type of cancer suspected
• The result of earlier medical tests

When a child has symptoms and signs of leukaemia, the doctor will ask about the child’s medical history and perform a physical examination. In addition, the following tests help diagnose AML ^​1​–

Blood tests

Complete blood count and cell type (called differential count) are blood tests. Therefore, These blood tests help to count the number of each type of blood cell using a microscope and to check if they look abnormal.

Bone marrow aspiration and biopsy

These two procedures are similar and often done simultaneously to evaluate the bone marrow, which is the fatty, spongy tissue found inside larger bones. Bone marrow has both a liquid and a solid part. A bone marrow aspiration takes a sample of the fluid using a needle. A bone marrow biopsy removes a small quantity of solid tissue using a needle.

A pathologist then reviews the samples in a lab. Pelvic bone located by the hip is a common site for bone marrow aspiration and biopsy. Doctors generally give a medication called “anesthesia” beforehand to numb the area. Anesthesia is a medication that blocks the awareness of pain.

Molecular and genetic testing

Your doctor may recommend running laboratory tests to identify specific genes, proteins, and other factors involved in leukaemia. Examining the genes in the leukaemia cells is essential because a buildup of mistakes (mutations) in the cell’s genes can cause AML. So, Identifying these mutations helps diagnose the specific subtype of AML and decide treatment options. Additionally, the results of those tests helps to monitor how good treatment is working ^​2​. Mentioned below are the more common molecular or genetic tests used for AML-

Cytochemical and immunohistochemical tests

It is laboratory tests help to determine the exact subtype of AML. In cytochemical tests, a specific dye is used that stains the different types of leukaemia cells differently based on the chemicals in the cells. For AML, immunohistochemical tests and a test known as flow cytometry are used to find markers on the surface of the leukaemia cells ^​3​. The different subtypes of leukaemia have different and unique combinations of cell surface markers.

Cytogenetics

It is a method to look at a cell’s chromosomes through a microscope to analyze the number, shape, size, and arrangement of the chromosomes to find genetic changes in the leukaemia cells. Sometimes, a chromosome part breaks off and reattaches to another chromosome, known as translocation. Other times, part of a chromosome is missing, known as deletion. A chromosome can be made more than once, most often called trisomy. Chromosome translocations, deletions, or trisomies are reason for some subtype of leukaemia .

Knowing if specific translocations may help doctors determine the AML subtype and plan the best treatment. Fluorescence-in-situ-hybridization (FISH) is a way to detect chromosome changes in cancer cells. So, it is being used often to help diagnose and find out the subtype of leukaemia ^​4​. This test is done on tissue removed in aspiration or biopsy.

Molecular genetic tests

These tests on leukaemia cells help find out if a person needs more or less chemotherapy or stem cell transplantation (also called bone marrow transplant). This type of testing looks for minimal genetic mutations, called sub-microscopic mutations. People with the FLT3 (pronounced “flit 3”) genetic mutation have a high risk of cancer coming back after treatment. For children with this type of AML, using a medical treatment known as stem cell or bone marrow transplantation may lengthen their lives when used after the first complete remission. New drugs are being tested that target FLT3-positive cells to determine if the drugs can better treat leukaemia. Simultaneously, research showed that children with two leukaemia cell gene mutations called nucleophosmin-1 (NPM1) and CEBPα have a better prognosis than those without these mutations. If the leukaemia has these mutations, the doctor may recommend chemotherapy without stem cell transplantation.

Whole-genome testing

Another name of this test is whole exome testing. It can look at a person’s entire genetic makeup. These are recently developed tools, and these testing methods are still emerging. They help to see genetic mutations that can lead to cancer. However, these tests are still only available in research studies where they are being used to determine if using these tests improves diagnosis, treatment, and cure.

References