What Is Acute Myeloid Leukemia (AML)?

Cancer starts when cells in the body begin to grow out of control. There are many kinds of cancer. Cells in nearly any part of the body can become cancer.

Leukemias are blood cancers. They start in cells that would normally develop into different types of blood cells. Most often, leukemia starts in early forms of white blood cells, but some leukemias start in other blood cell types.

There are several types of leukemia. They are divided based mainly on whether the leukemia is acute (fast growing) or chronic (slower growing), and whether it starts in myeloid cells or lymphoid cells.

Acute myeloid leukemia (AML) starts in the bone marrow, the soft inner part of certain bones, where new blood cells are made. Most often AML quickly moves from the bone marrow into the blood. It can sometimes spread to other parts of the body including the lymph nodes, liver, spleen, central nervous system (brain and spinal cord), and testicles. Sometimes leukemia cells form a tumor called a myeloid sarcoma.

Different types of AML are discussed in Acute Myeloid Leukemia (AML) Subtypes and Prognostic Factors.

How is acute myeloid leukemia (AML) different from other leukemias? 

Acute myeloid leukemia (AML) has many other names, including acute myelocytic leukemia, acute myelogenous leukemia, acute granulocytic leukemia, and acute non-lymphocytic leukemia.

• Most often, AML develops in early forms of myeloid cells (see below) that would normally turn into white blood cells. But it can also develop in early forms of other myeloid cells.
• AML tends to progress quickly, and it usually needs to be treated right away.
• AML is one of the most common leukemias in adults.
• There are different subtypes of AML. Most subtypes are classified on how mature (developed) the leukemia cells are, and how different they are from normal cells.

How acute myeloid leukemia (AML) affects normal bone marrow, blood, and lymph tissue

To understand leukemia, it helps to know about the blood and lymph systems.

Bone marrow

Bone marrow is the soft inner part of certain bones. It is made up of blood-forming cells, fat cells, and supporting tissues. A small fraction of the blood-forming cells are blood stem cells.

Inside the bone marrow, blood stem cells develop into new blood cells. During this process, the cells become either lymphocytes (a kind of white blood cell) or other blood-forming cells, which are types of myeloid cells. Myeloid cells can develop into red blood cells, white blood cells (other than lymphocytes), or into the cells that make platelets. Some of these myeloid cells are the ones that are abnormal in AML.

Types of blood cells

There are 3 main types of blood cells:

• Red blood cells (RBCs) carry oxygen from the lungs to all other tissues in the body and take carbon dioxide back to the lungs to be removed.
• Platelets are small pieces of cells that split off from a type of bone marrow cell called a megakaryocyte. Platelets are important in stopping bleeding. They help plug up holes in blood vessels caused by cuts or bruises.

White blood cells (WBCs) help the body fight infections. There are different types of WBCs, which work in slightly different ways.