Types of Leukemia in Children

Leukemias are named after the type of white blood cell that is affected. The most common types in children are acute lymphoblastic leukemia and acute myelogenous leukemia. At MSK Kids, our leukemia experts treat all kinds of leukemia in children, teens, and young adults.

Acute Lymphoblastic Leukemia

Acute leukemia of the lymphoid cells is called acute lymphoblastic leukemia (ALL). It is the most common type and accounts for 85 percent of leukemias in children. There are three types of lymphoid cells (lymphocytes):  B cells, which make antibodies to help fight infection, T cells, which help B cells make those antibodies, and natural killer cells that attack cancer cells and viruses. In children with ALL, there are too many abnormal lymphocytes and they are unable to fight infections well. These abnormal lymphocytes are leukemia cells. As their numbers increase in the blood and bone marrow, they crowd out healthy red and white blood cells and platelets. As a result, children with ALL may experience more infections and anemia and bruise or bleed more easily.

Acute Myelogenous Leukemia

Acute leukemia of myeloid white blood cells is called acute myelogenous leukemia (AML) and is responsible for nearly 15 percent of childhood leukemias. AML is also called acute myeloid leukemia, acute myeloblastic leukemia, acute granulocytic leukemia, and acute nonlymphocytic leukemia. There are several types of myeloid cells and their main role is to fight infections, particularly those caused by bacteria. Red blood cells and platelets also come from myeloid cells.

The immature white blood cells in children with AML are called myeloblasts. They are unable to work as well as normal white blood cells and can cause similar symptoms as ALL due to overcrowding of myeloblasts in the blood and bone marrow and insufficient numbers of healthy white blood cells. Children with AML may also experience infections and anemia and bruise or bleed easily. Subtypes of AML include acute promyelocytic leukemia (APL) and a rare disease known as juvenile myelomonocytic leukemia (JMML).

Chronic Myelogenous Leukemia

Chronic myelogenous leukemia (CML) is a third type, but it is much rarer in children than in adults. It is often caused by a swap of genetic material between two chromosomes, leading to the formation of a new gene called the BCR-ABL gene. This gene tells blood cells to make too much of an enzyme called tyrosine kinase, which causes too many leukemia cells to be made in the bone marrow and makes patients prone to infection, anemia, and easy bleeding. There are oral medications now used to treat CML by blocking tyrosine kinase.

Infant Leukemia

Infant leukemia is a rare blood cancer in babies younger than 1 year old. Some babies are born with it. The 2 main types are acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML).

Infant leukemia can be harder to treat than leukemia in older children. It often grows fast and may not respond as well to chemotherapy. One common gene change (mutation) is called KMT2A rearrangement. This change is seen more often in babies than in older children. 

In babies with AML, leukemia is more likely to affect the brain, spinal cord, or skin. In babies with ALL, a high white blood cell count is common at diagnosis. Chemotherapy may work well at first, but the leukemia is more likely to come back. Babies are also more likely to have serious side effects from strong treatment.