Cancers and Tumors
Types of Leukemia
Acute and Chronic Leukemia
There are two major types of leukemia – acute leukemia and chronic leukemia. Almost all children who have leukemia have an acute form. Acute leukemia grows rapidly and worsens quickly if your child does not get treatment.
Chronic leukemia develops more slowly.
There are two types of acute leukemia. They are named for the type of blood cell that is cancerous.
Acute lymphocytic leukemia (ALL)
Acute lymphocytic leukemia is the most common type of cancer in children. It arises from white blood cells called lymphocytes.
Healthy lymphocytes circulate in the lymph system and bloodstream to fight infection. In ALL, these cells do not mature the way they should, so they cannot fight infection well. As a result, children with ALL are more prone to infections.
Also in ALL the body makes too many immature lymphocytes. They crowd out other types of healthy white blood cells as well as red blood cells and platelets. So children with ALL may get symptoms of low red blood cells, like anemia, and low platelets, like bleeding or bruising easily.
There are two types of lymphocytes: B cells and T cells. Cancer is more common in B cells than T cells.
ALL is also called acute lymphoblastic leukemia.
Acute myelogenous leukemia (AML)
Acute myelogenous leukemia can arise from many types of blood cells that are still developing.
All the cells affected by AML start as myeloid stem cells. In a healthy body, some of myeloid stem cells will turn into red blood cells, some into platelets and some into myeloblasts. The myeloblasts go on to become white blood cells called granulocytes.
In AML the myeloid stem cells don't mature the way they should. Usually they turn into myeloblasts, but then the myeloblasts don't turn into healthy granulocytes. The immature myeloblasts cannot do the job that granulocytes would normally do.
As in ALL, the immature cells crowed out other healthy blood cells. This is what causes many of the symptoms of AML.
Certain diseases caused by problems with genes (genetic disorders) increase a child's risk of getting AML. These include Down syndrome and Fanconi anemia.
Chronic leukemia is much less common in children than acute leukemia.
Chronic myelogenous leukemia (CML)
About 2 to 3% of children with leukemia have chronic myelogenous leukemia. It is like AML except that some blood cells develop and work fine, so the early part of the disease is often less severe.
CML in children is treated with chemotherapy given by mouth and for some patients a hematopoietic cell, or stem cell, transplant.
Other Types of Leukemia
Children can have other kinds of leukemia, too, such as JMML and MDS.
Juvenile myelomonocytic leukemia (JMML)
About 1 to 2% of children with leukemia have juvenile myelomonocytic leukemia. It mainly affects children younger than 4 years old. JMML is a very hard type of leukemia to treat.
The current treatment includes chemotherapy and a hematopoietic cell, or stem cell, transplant.
Myelodysplastic syndrome (MDS)
Another disease related to leukemia is called myelodysplastic syndrome, or MDS. In MDS, the child's bone marrow does not make enough white blood cells, red blood cells and platelets. MDS can range from mild to severe.
Most of the content in this section is about ALL or AML. They are the most common kinds of leukemia in children. Your child's health care team can give you more details about MDS or any type of leukemia your child has.