Childhood Leukemia Subtypes

The type and subtype of leukemia a child has plays a major role in both treatment options and the child’s outlook (prognosis). Determining the type (acute lymphocytic leukemia (ALL), acute myeloid leukemia (AML), etc.) and subtype of the leukemia is done by testing samples of the blood, bone marrow, and sometimes lymph nodes or cerebrospinal fluid (CSF), as described in Tests for Childhood Leukemia.

Be sure to ask your health care team or your child's doctor if you have any questions about the subtype of your child’s leukemia.

Acute lymphocytic (lymphoblastic) leukemia (ALL)

Acute lymphocytic leukemia (ALL) is a fast-growing cancer of lymphocyte-forming cells called lymphoblasts. There are several subtypes of ALL, which are based mainly on:

• The type of lymphocyte (most often B cell or T cell) the leukemia cells come from (and how mature the cells are). This is known as the immunophenotype of the leukemia.
• If the leukemia cells have certain gene or chromosome changes

B-cell ALL

Most often in children with ALL, the leukemia starts in early forms of B cells. There are several subtypes of B-cell ALL. Mature B-cell ALL (also called Burkitt leukemia), a rare subtype, is essentially the same as Burkitt lymphoma (a type of non-Hodgkin lymphoma) and is treated the same way. (See Treatment of Non-Hodgkin Lymphoma in Children, by Type and Stage.)

T-cell ALL

This type of leukemia affects older children more than B-cell ALL does. It often causes an enlarged thymus (a small organ in front of the windpipe), which can sometimes lead to breathing problems. It may also spread to the cerebrospinal fluid (CSF, the fluid that surrounds the brain and spinal cord) early in the course of the disease.

For more detailed information on the subtypes of ALL, see Acute Lymphocytic Leukemia (ALL) Subtypes and Prognostic Factors.

Aside from the subtype of ALL, other factors are important in determining a child's outlook (prognosis). These are described in Prognostic Factors in Childhood Leukemia.

Acute myeloid leukemia (AML)

Acute myeloid leukemia (AML) is typically a fast-growing cancer that starts in one of the following types of early (immature) bone marrow cells:

• Myeloblasts: These cells normally form white blood cells called granulocytes (neutrophils, eosinophils, and basophils).
• Monoblasts: These cells normally become white blood cells called monocytes and macrophages.
• Erythroblasts: These cells mature into red blood cells.
• Megakaryoblasts: These cells normally become megakaryocytes, the cells that make platelets.

AML has many subtypes, which are based mainly on:

• The type of bone marrow cell the leukemia cells come from, and how mature the cells are (the immunophenotype of the leukemia)
• If the leukemia cells have certain gene or chromosome changes
• If the leukemia is related to the treatment of an earlier cancer (with chemotherapy or radiation)
• If the child with leukemia has Down syndrome

Acute promyelocytic leukemia (APL) is a special subtype of AML. It is treated differently from other subtypes of AML, and it tends to have a better outlook.

For more detailed information on the subtypes of AML, see Acute Myeloid Leukemia (AML) Subtypes and Prognostic Factors.

Aside from the AML subtype, other factors are important in determining a child’s outlook (prognosis). These are described in Prognostic Factors in Childhood Leukemia.

Chronic myeloid leukemia (CML)

Chronic myeloid leukemia (CML) is typically a slower-growing cancer of early (immature) myeloid bone marrow cells. CML is not common in children, but it can occur.

CML does not have subtypes. Instead, the course of CML has 3 phases, based mainly on the number of immature white blood cells – myeloblasts (or blasts) – that are seen in the blood or bone marrow. CML can sometimes progress to more advanced phases over time.

Chronic phase of CML

In this earliest phase, children usually have fairly mild symptoms (if any), and the leukemia usually responds well to standard treatments. Most children are in the chronic phase when they are diagnosed.

Accelerated phase of CML

Children whose CML is in accelerated phase may have symptoms such as fever, night sweats, poor appetite, and weight loss. CML in the accelerated phase might not respond as well to treatment as CML in the chronic phase.

Blast phase (also called acute phase or blast crisis) of CML

In this phase, the leukemia cells often spread to tissues and organs outside the bone marrow. Children with CML in this phase often have fever, poor appetite, and weight loss. At this point the CML acts much like an aggressive acute leukemia (AML or, less often, ALL).

For more detailed information on the phases of CML, see Phases of Chronic Myeloid Leukemia.