About AML

Justine was diagnosed with acute myeloid leukemia (AML), a cancer of the myeloid line of cells that is characterized by the rapid proliferation of abnormal cells which accumulate in the bone marrow and interfere with the production of normal blood cells.

Acute Myelogenous Leukemia (AML)

Acute myelogenous leukemia (AML) is a cancer of one of the following types of early (immature) bone marrow cells:

• myeloblasts: These cells normally form granulocytes (neutrophils, eosinophils, and basophils). 
• monoblasts: These cells normally become monocytes and macrophages. 
• erythroblasts: These cells mature into red blood cells. 
• megakaryoblasts: These cells normally become megakaryocytes, the cells that make platelets.

AML has several subtypes, based on the type of cell involved and how mature it is. Although several lab tests can be helpful in diagnosing AML, the subtypes of AML are classified mainly by their morphology (appearance under the microscope), using routine and cytochemical stains. It may also be useful to look for changes in the genes or chromosomes of the leukemia cells.

There are 8 subtypes of AML: M0 to M7 (the “M” refers to myeloid).

M0: This subtype of AML is made up of very immature cells —so immature that they can’t be labeled according to the types of cells listed above. This subtype can only be distinguished from ALL by flow cytometry because the cells lack any distinct features that can be seen by microscope. (Flow cytometry is explained in the section, “How Is Childhood Leukemia Diagnosed?”) This type of leukemia is very rare in children.

M1: This subtype is made up of immature myeloblasts. It can be recognized by the way the cells look under the microscope after using cytochemical stains.

M2: This subtype is composed of slightly more mature forms of myeloblasts. It is the most common subtype of AML in children, making up a little more than 1 out of every 4 cases.

M3: The M3 subtype is also known as acute promyelocytic leukemia (APL). It is made up of promyelocytes, which are a more mature form of myeloblast. Treatment of APL is different than for other subtypes of AML, as it involves some newer drugs.

M4: This subtype is known as acute myelomonocytic leukemia. The cells are an early form of monoblast. The M4 subtype is common in children less than 2 years of age.

M5: This is known as acute monocytic leukemia. It is made up of monoblasts. Like the M4 subtype, it is more common in children less than 2 years of age.

M6: This subtype of AML is known as acute erythroblastic leukemia (or acute erythroleukemia). It starts in erythroblasts, the cells that normally mature into red blood cells. It is very rare in children.

M7: This subtype is also known as acute megakaryoblastic leukemia. The cells are megakaryoblasts. They may show a unique “budding,” resembling the way platelets normally form from normal megakaryocytes.

(From the American Cancer Society)