Childhood acute myeloid leukemia (AML) is a type of cancer in which the bone marrow makes a large number of abnormal blood cells.
Cancers that are acute usually get worse quickly if they are not treated. Cancers that are chronic usually get worse slowly. Acute myeloid leukemia (AML) is also called acute myelogenous leukemia, acute myeloblastic leukemia, acute granulocytic leukemia, or acute nonlymphocytic leukemia.
In AML, the myeloid stem cells usually develop into a type of immature white blood cell called myeloblasts (or myeloid blasts). The myeloblasts, or leukemia cells, in AML are abnormal and do not become healthy white blood cells. The leukemia cells can build up in the blood and bone marrow so there is less room for healthy white blood cells, red blood cells, and platelets. When this happens, infection, anemia, or easy bleeding may occur. The leukemia cells can spread outside the blood to other parts of the body, including the central nervous system (brain and spinal cord), skin, and gums. Sometimes leukemia cells form a solid tumor called a granulocytic sarcoma or chloroma.
There are subtypes of AML based on the type of blood cell that is affected. The treatment of AML is different when it is a subtype called acute promyelocytic leukemia (APL) or when the child has Down syndrome.
Other myeloid diseases can affect the blood and bone marrow.
Chronic myelogenous leukemia
In chronic myelogenous leukemia (CML), too many bone marrow stem cells develop into a type of white blood cell called granulocytes. Some of these bone marrow stem cells never become mature white blood cells. These are called blasts. Over time, the granulocytes and blasts crowd out the red blood cells and platelets in the bone marrow. CML is rare in children.
Juvenile myelomonocytic leukemia
Juvenile myelomonocytic leukemia (JMML) is a rare childhood cancer that occurs more often in children around the age of 2 years. In JMML, too many bone marrow stem cells develop into 2 types of white blood cells called myelocytes and monocytes. Some of these bone marrow stem cells never become mature white blood cells. These immature cells, called blasts, are unable to do their usual work. Over time, the myelocytes, monocytes, and blasts crowd out the red blood cells and platelets in the bone marrow. When this happens, infection, anemia, or easy bleeding may occur.
Transient myeloproliferative disorder
Transient myeloproliferative disorder (TMD) is a disorder of the bone marrow that can develop in newborns who have Down syndrome. This disorder usually goes away on its own within the first 3 weeks of life. Infants who have Down syndrome and TMD have an increased chance of developing AML before the age of 3 years.
Myelodysplastic syndromes
In myelodysplastic syndromes (MDS), the bone marrow makes too few red blood cells, white blood cells, and platelets. These blood cells may not mature and enter the blood. The treatment for MDS depends on how much lower than normal the number of red blood cells, white blood cells, or platelets is. MDS may progress to AML.
The risk factors for developing childhood AML, childhood CML, JMML, TMD, and MDS are similar.
Anything that increases your risk of getting a disease is called a risk factor. Having a risk factor does not mean that you will get cancer; not having risk factors doesn’t mean that you will not get cancer. People who think they may be at risk should discuss this with their doctor. Possible risk factors for childhood AML, childhood CML, JMML, TMD, and MDS include the following:
· Having a brother or sister, especially a twin, with leukemia.
· Being Hispanic.
· Being exposed to cigarette smoke or alcohol before birth.
· Having a history of MDS (also called preleukemia) or aplastic anemia.
· Past treatment with chemotherapy or radiation therapy.
· Being exposed to ionizing radiation or chemicals such as benzene.
· Having certain genetic disorders, such as
o Down syndrome.
o Fanconi anemia.
o Neurofibromatosis type 1.
o Noonan syndrome.
o Shwachman-Diamond syndrome.
Possible signs of childhood AML, childhood CML, JMML, or MDS include fever, feeling tired, and easy bleeding or bruising.
These and other symptoms may be caused by childhood AML, childhood CML, JMML, or MDS. Other conditions may cause the same symptoms. A doctor should be consulted if any of the following problems occur:
· Fever with or without an infection.
· Night sweats.
· Shortness of breath.
· Weakness or feeling tired.
· Easy bruising or bleeding.
· Petechiae (flat, pinpoint spots under the skin caused by bleeding).
· Pain in the bones or joints.
· Pain or feeling of fullness below the ribs.
· Painless lumps in the neck, underarm, stomach, groin, or other parts of the body. When seen in childhood AML, these lumps, called leukemia cutis, may be blue or purple.
· Painless lumps that are sometimes around the eyes. These lumps, called chloromas, are sometimes seen in childhood AML and may be blue-green.
· An eczema -like skin rash.
The symptoms of TMD may include the following:
· Swelling all over the body.
· Shortness of breath.
· Trouble breathing.
· Weakness or feeling tired.
· Pain below the ribs.
Tests that examine the blood and bone marrow are used to detect (find) and diagnose childhood AML, childhood CML, JMML, TMD, and MDS.
The following tests and procedures may be used:
· Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
· Complete blood count (CBC) with differential.
· Blood chemistry studies: A procedure in which a blood sample is checked to measure the amounts of certain substances released into the blood by organs and tissues in the body. An unusual (higher or lower than normal) amount of a substance can be a sign of disease in the organ or tissue that makes it.
· Chest x-ray: An x-ray of the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
· Peripheral blood smear: A procedure in which a sample of blood is checked for blast cells, number and kinds of white blood cells, number of platelets, and changes in the shape of the blood cells.
· Biopsy: The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer.
· Cytogenetic analysis: A laboratory test in which cells in a sample of blood or bone marrow are viewed under a microscope to look for certain changes in the chromosomes.
· Immunophenotyping: A process used to identify cells, based on the types of antigens or markers on the surface of the cell, that may include special staining of the blood and bone marrow cells. This process is used to diagnose the subtype of AML by comparing the cancer cells to normal cells of the immune system.
· FISH (fluorescence in situ hybridization): A laboratory technique used to look at genes or chromosomes in cells and tissues. Pieces of DNA that contain a fluorescent dye are made in the laboratory and added to cells or tissues on a glass slide. When these pieces of DNA bind to specific genes or areas of chromosomes on the slide, they light up when viewed under a microscope with a special light.
· Reverse transcription–polymerase chain reaction test (RT–PCR): A laboratory test in which cells in a sample of tissue are studied using chemicals to look for certain changes in the structure or function of genes.
· Lumbar puncture: A procedure used to collect cerebrospinal fluid from the spinal column. This is done by placing a needle into the spinal column. This procedure is also called an LP or spinal tap.
Certain factors affect prognosis (chance of recovery) and treatment options.
The prognosis (chance of recovery) and treatment options for childhood AML depend on the following:
· The age of the child at diagnosis.
· The race or ethnic group of the child.
· Whether the child is greatly overweight.
· Number of white blood cells in the blood at diagnosis.
· Whether the AML was caused by previous anticancer treatment.
· The subtype of AML.
· Whether there are certain chromosome or gene changes in the leukemia cells.
· Whether the child has Down syndrome. Most children with AML and Down syndrome can be cured of their leukemia.
· Whether the child has leukemia in the central nervous system (brain and spinal cord).
· How quickly the leukemia responds to initial treatment.
· Whether the AML is newly diagnosed or has recurred (come back) after being treated.
· The length of time since treatment ended, for AML that has recurred.
The prognosis and treatment options for childhood CML depend on how long it has been since the patient was diagnosed and how many blast cells are in the blood.
The prognosis (chance of recovery) and treatment options for JMML depend on the following:
· The age of the child at diagnosis.
· How many red blood cells, white blood cells, or platelets are in the blood.
· Whether the JMML is untreated or has recurred after treatment.
The prognosis (chance of recovery) and treatment options for MDS depend on the following:
· Whether the MDS was caused by previous cancer treatment.
· How low the numbers of red blood cells, white blood cells, or platelets are.
· Whether the MDS is untreated or has recurred after treatment.
Once childhood acute myeloid leukemia (AML) has been diagnosed, tests are done to find out if the cancer has spread to other parts of the body.
The extent or spread of cancer is usually described as stages. In childhood acute myeloid leukemia (AML), the subtype of AML and whether the leukemia has spread outside the blood and bone marrow are used, instead of the stage, to plan treatment. The following tests and procedures may be used to determine if the leukemia has spread:
· Lumbar puncture: A procedure used to collect cerebrospinal fluid (CSF) from the spinal column. This is done by placing a needle into the spinal column. This procedure is also called an LP or spinal tap.
· Biopsy of the testicles, ovaries, or skin: The removal of cells or tissues from the testicles, ovaries, or skin so they can be viewed under a microscope to check for signs of cancer. This is done only if something unusual about the testicles, ovaries, or skin is found during the physical exam..
There are three ways that cancer spreads in the body.
When cancer cells spread outside the blood, a solid tumor may form. This process is called metastasis. The three ways that cancer cells spread in the body are:
· Through the blood. Cancer cells travel through the blood, invade solid tissues in the body, such as the brain or heart, and form a solid tumor.
· Through the lymph system. Cancer cells invade the lymph system, travel through the lymph vessels, and form a solid tumor in other parts of the body.
· Through solid tissue. Cancer cells that have formed a solid tumor spread to tissues in the surrounding area.
The new (metastatic) tumor is the same type of cancer as the primary cancer. For example, if leukemia cells spread to the brain, the cancer cells in the brain are actually leukemia cells. The disease is metastatic leukemia, not brain cancer.
There is no standard staging system for childhood AML, childhood chronic myelogenous leukemia (CML), juvenile myelomonocytic leukemia (JMML), transient myeloproliferative disorder (TMD), or myelodysplastic syndromes (MDS).
Childhood AML is described as newly diagnosed, in remission, or recurrent.
Newly diagnosed childhood AML
Newly diagnosed childhood AML has not been treated except to relieve symptoms such as fever, bleeding, or pain, and one of the following is true:
· More than 20% of the cells in the bone marrow are blasts (leukemia cells).
or
· Less than 20% of the cells in the bone marrow are blasts and there is a specific change in the chromosome.
Childhood AML in remission
In childhood AML in remission, the disease has been treated and the following are true:
· The complete blood count is almost normal.
· Less than 5% of the cells in the bone marrow are blasts (leukemia cells).
· There are no signs or symptoms of leukemia in the brain, spinal cord, or other parts of the body.
Recurrent Childhood Acute Myeloid Leukemia
Recurrent childhood acute myeloid leukemia (AML) has recurred (come back) after it has been treated. The cancer may come back in the blood and bone marrow or in other parts of the body, such as the central nervous system (brain and spinal cord.
National Cancer Institute