acute myeloid leukemia
Meaning of acute myeloid leukemia: The damage comes less from the tumor itself than from what stops being made once the marrow fills with blasts.
Definition of acute myeloid leukemia
Acute myeloid leukemia is a fast-moving cancer of the bone marrow in which immature myeloid cells, called blasts, multiply and fill the space. They crowd out normal production, so healthy red cells, white cells and platelets fall, bringing tiredness, infection and easy bleeding. The blasts also spill into the bloodstream, where they can be seen and counted.
What separates it from the other leukemias?
| Cells involved | Myeloid line | Lymphoid line |
|---|---|---|
| Immature blasts, fast course | Acute myeloid leukemia | Acute lymphocytic leukemia |
| Maturing cells, slow course | Chronic myeloid leukemia | Chronic lymphocytic leukemia |
Every leukemia is named on two axes: which family of blood-forming cells it came from, and whether those cells are frozen as blasts or continue maturing. Myeloid cells give rise to red cells, platelets and most white cells; lymphoid cells give rise to lymphocytes. The split is settled by the markers on the cell surface rather than by appearance alone, though needle-shaped inclusions called Auer rods, when they are present, identify a blast as myeloid. It matters because the two lines respond to completely different drugs, so the question is answered before treatment is planned rather than after. Acute lymphocytic leukemia looks similar on a blood count and is treated on a different footing entirely.
How is it diagnosed?
A blood count showing anemia, low platelets and circulating blasts prompts a bone marrow sample. The diagnosis rests on the proportion of blasts, the markers they carry, and the chromosome and gene changes inside them. Certain genetic changes now establish the diagnosis regardless of how many blasts are present, and the same changes sort cases into groups whose outlook and treatment differ sharply, so the genetic report forms part of the diagnosis rather than an addition to it. The disease can also arise out of an earlier marrow disorder or years after chemotherapy for another cancer, and those forms behave differently again.
Why is one subtype treated differently?
Acute promyelocytic leukemia is defined by an exchange of material between two chromosomes that fuses part of a receptor for vitamin A to another gene. The fusion jams the cells at a single stage of maturing, and those cells release material that sets off widespread clotting and bleeding at the same time, so severe bleeding, not marrow failure, is the early threat. The same fault makes it unusually treatable, because a form of vitamin A releases the block and pushes the cells to finish maturing instead of killing them. That combination of urgency and opportunity is why a newly suspected case is checked for this subtype immediately.
Also known as
Used in a sentence
Bone marrow biopsy confirmed a diagnosis of acute myeloid leukemia.
Good to know
Acute myeloid leukemia arises from the myeloid cell lineage in the bone marrow, which distinguishes it from the lymphocytic leukemias arising from lymphocytes, a difference that determines the treatment approach used.
Word origin
Where “acute myeloid leukemia” comes from
Formed from Greek leukos, meaning white, and haima, meaning blood, combined with myelo-, meaning marrow, describing a leukemia arising from the bone marrow's myeloid cell lineage.