AML Foundations

Question 1

what does AML stand for?

Answer 1

acute myeloid leukemia

acute = able to quickly progress

myeloid = arising from a non-lymphoid lineage

leukemia = cancer of the blood

Question 2

what is AML?

Answer 2

AML is a cancer of the blood arising from myeloid precursor cells that has the possibility to progress quickly if left untreated

Question 3

what population is AML most common in?

Answer 3

most commonly seen in adults over the age of 45

Question 4

how do definitely diagnose AML?

Answer 4

a blood smear or bone marrow biopsy must show ≥ 20% blasts or blast equivalents

Question 5

what’s the main morphologic feature in AML?

Answer 5

abundance of myeloblasts

blasts are the earliest most immature precursor cells of a lineage

they usually have giant nucleus compared to the cytoplasm , fine smooth chromatin and visible nucleoli

Question 6

what is a blast equivalent?

Answer 6

in some types of AML, the malignant cell is a little more mature than a blast

ex. i

n acute promyelocytic leukemia, for example, there are a ton of malignant promyelocytes (but not very many myeloblasts)

in these types of AML, we use the term “blast equivalent” instead of blasts for whatever immature call that is proliferating the most

Question 7

why would someone with AML show symptoms of bone marrow failure?

Answer 7

patients with AML must have a bone marrow biopsy or blood smear showing ≥ 20% blasts or blast equivalents

so they’re gonna show symptoms of bone marrow failure because their BM is busy erroneously producing malignant cells and does not have the resources or space to create normal amounts of WBCs, RBCs, or platelets

Question 8

what will the CBC of someone will AML show?

Answer 8

neutropenia = low neutrophils = increased risk of infection

thrombocytopenia = too few platelets = increased risk of bruising and bleeding

anemia due do too few RBCs

Question 9

what does the blood smear of an AML patient show?

Answer 9

at least 20% blasts

cells containing Auer rods

Question 10

what are Auer rods?

Answer 10

cytoplasmic inclusions that are formed from the abnormal fusion of azurophilic, or primary, granules

azurophilic granules are contained in neutrophils, which are formed from myeloid precursor cells.

literally lok like bars sticking out of the nucleus

Question 11

how do you classify AML into subtypes?

Answer 11

there’s 8 FAB classifications of AML that depend on what type of cells the disease developed from and how mature the cells were at diagnosis

AML doesn’t grow like a solid tumor so it’s not staged like most cancers

classification of AML depends on other information such as the subtype, the patient’s age, and other lab results

Question 12

what is the M0 FAB subtype?

Answer 12

Acute myeloblastic leukemia with minimal differentiation

Question 13

what is the M1 FAB subtype?

Answer 13

Acute myeloblastic leukemia without maturation

Question 14

what is the M2 FAB subtype?

Answer 14

acute myeloblastic leukemia with maturation

Question 15

what is the M3 FAB subtype?

Answer 15

Acute promyelocytic leukemia (APL)

Question 16

what is the M4 FAB subtype?

Answer 16

Acute myelomonocytic leukemia

Question 17

what is the M5 FAB subtype?

Answer 17

Acute monocytic leukemia

Question 18

what is the M6 FAB subtype?

Answer 18

acute erythroid leukemia

Question 19

what is the M7 FAB subtype?

Answer 19

acute megakaryoblastic leukemia

Question 20

what cell type of FAB subtypes M0-M3 involve?

Answer 20

neutrophil precursors

but myeloid progenitor cells can form RBCs, platelets, basophils, neutrophils, eosinophils, and monocytes.

so it makes sense that it is possible for AML to arise from any of these cell lines

Question 21

what cell type of FAB subtypes M4-M5 involve?

Answer 21

monocytic precursors

Question 22

what’s the WHO system of classifying AML?

Answer 22

a newer system to classify AML into five categories, which take into consideration genetics (chromosome translocations), immunophenotype, morphology, and clinical features

Question 23

what is the WHO system of classifying AML?

Answer 23

1. AML with recurrent genetic abnormalities
2. AML with myelodysplasia-related changes
3. Therapy-related AML
4. AML, not otherwise specified
5. Myeloid sarcoma

Question 24

How does the classification of AML differ from the FAB and the WHO classification systems?

Answer 24

The FAB system classifies AML based on cellular morphology while the WHO system classifies AML based on genetics, such as chromosomal translocations, as well as immunophenotype and morphology.

Question 25

what’s the most well-known FAB subtype?

Answer 25

M3, aka acute promyelocytic leukemia (APL)

Question 26

what causes APL?

Answer 26

most common AML

APL is due to a translocation between chromosomes 15 and 17 [t(15;17)] and may account for 5-20% of all cases of AML

Question 27

how do you treat APL?

Answer 27

all-trans retinoic acid, a form of vitamin A

it prompts differentiation of the WBCs, effectively putting an end to the predominance of blast cells and, therefore, the cancer

Question 28

Acute promyelocytic leukemia (AML subtype M3) is due to a translocation between which two chromosomes?

Answer 28

APL is due to a translocation between chromosomes 15 and 17. This is written as t(15;17).