Childhood Acute Myeloid Leukemia

by National Cancer Institute

Leukemia and other diseases of the blood and bone marrow may affect red blood cells, white blood cells, and platelets.

Normally, the bone marrow makes stem cells (immature cells) that develop into mature blood cells. There are three types of mature blood cells:

• Red blood cells that carry oxygen and other materials to all tissues of the body.
• White blood cells that fight infection and disease.
• Platelets that help prevent bleeding by causing blood clots to form.

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 stem cells usually develop into a type of white blood cell called myeloblasts (or myeloid blasts). The myeloblasts, or leukemia cells, in AML are abnormal and do not mature into healthy white blood cells. These blood cells are unable to do their usual work and 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 younger than 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, 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 myelodysplastic syndromes depends on how much lower than normal the number of red blood cells, white blood cells, or platelets is. Myelodysplastic syndromes may progress to AML.

The risk factors for developing childhood AML, childhood CML, JMML, TMD, and myelodysplastic syndrome are similar.

Anything that increases your risk of getting a disease is called a risk factor. Possible risk factors for childhood AML, childhood CML, JMML, TMD, and myelodysplastic syndrome 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 myelodysplastic syndrome (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 Down syndrome, Fanconi's anemia, neurofibromatosis type 1, or Noonan's syndrome.

Possible signs of childhood AML, childhood CML, JMML, or myelodysplastic syndromes include fever, feeling tired, and easy bleeding or bruising.

These and other symptoms may be caused by childhood AML, childhood CML, JMML, or myelodysplastic syndromes. 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.

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