AML

Question 1

Give a brief background of AML

Answer 1

This is a complex disease particularly common in the elderly - 70% of adult acute leukaemia
Peak prevalence around 60
Acute myeloid refers to >20% blasts

Question 2

What is the aetiology of AML?

Answer 2

External risk factors:
Benzene - primarily found in gasoline and by-products
Car fumes
Smoking
Exposure to radiations

Question 3

What are some factors that can contribute to AML?

Answer 3

Age
Familiar types
Previous treatment for cancer - treatment-related AML

Question 4

Describe the presenting symptoms of AML

Answer 4

Tiredness
Bruising and bleeding 
Shortness of Breath
Weight Loss
Infections

Question 5

How is diagnosis of AML made?

Answer 5

Blood count - anaemia and raised blasts with reduced neutrophils
Peripheral Blood and bone marrow morphology- many different subtypes
Immunophenotype
Cytogenetics
Molecular tests - confirm cytogenetics and try to identify a molecular target for minimal residual disease monitoring

Question 6

How is AML classified?

Answer 6

FAB classification
AML Mo
AML M1
AML M2 
AML M3 - apml
AML M4 - eo type
AML M5
AML M6
AML M7

Question 7

Where do the leukaemias arise?

Answer 7

AML M0 - M5 occur in the bone marrow

AMLM6 and M7 occur in the peripheral blood

Question 8

Describe the appearance of AML M0 and M1 on the blood film

Answer 8

Very immature blast cells
Prominent nucleoli
Very fine/sometimes absent granulations
Hard to tell the difference between M0 and M1
3-4 normal cells should fit into a blast cell

Question 9

How do you tell the difference between AML and ALL on the blood film?

Answer 9

AML has abundant cytoplasm, coarse chromatin appearance, 3/4 nucleoli visible, granules and auer rods visible in cytoplasm

ALL has a rim of cytoplasm, with fine chromatin, 1-2 nucleoli and absence of granules and auer rods

Question 10

What is the significance of auer rod findings?

Answer 10

Any presence of auer rods in the cytoplasm - myeloid leukaemia
If there is one or two it is M2 if there are more then it is M3

Question 11

What is seen in the morphology of M4 with eosinophilia?

Answer 11

Granules all over, they are much bigger, more prominent and cover the nucleus too
They(eosinophils) have a mature nucleus, some may have 1 lobe, some may have more than 2

Question 12

What is seen in the morphology of AML M5?

Answer 12

Leukaemia which classically presents with gum hypertrophy

Monocytes have a kidney shaped nucleus

Question 13

How are the granules in myeloid cells exploited for identification?

Answer 13

The granules are absent in lymphoid cells so you can stain for myeloperoxidase which is contained in the granules

Question 14

Which stains are AML positive for?

Answer 14

MPO and sudan Black

Question 15

Describe the flow cytometry for AML

Answer 15

CD13 CD33 myeloid markers
CD34 - early precursor marker
HLA-DR - also immature myeloid marker
CD11c - myeloid marker
CD117 - Early Myeloid marker

Question 16

What is particular about AML M0?

Answer 16

It is negative for all differentiation markers - MPO, CD117, CD33 apart from CD34 and HLA-dr

Question 17

What is seen in AML M1 and M2?

Answer 17

CD117 CD13, and CD33

and CD34 and HLA-DR

Question 18

What flow cytometry is seen in AML M4?

Answer 18

CD34, CD117, Cd13 and CD33

and CD16 and CD64 for monocytic differentiation

Question 19

What is the intermediate risk group?

Answer 19

Everything in between, so normal karyotype or cytogenetics abnormalities not included in other categories, being over the age of 60

Question 20

Describe a study which investigates the prognosis difference between younger and elderly patients

Answer 20

Applebaum et al 2005 found that:
Drug resistance: <56: 33% >75:57%
Favourable cytogenetics <56: 17% >75:4%
Unfavourable cytogenetics: <56: 35%, >75: 51%

Question 21

What family of genes are affected in AML?

Answer 21

Core binding factor genes
These are involved primarily in myeloid cell differentiation, mutation in them leads to arrest of cell differentiation and proliferation of immature cells instead

Question 22

Which study investigated the CBF? What is the importance of CBFbeta?

Answer 22

de Brujin M 2004
Core binding factors compose non DNA binding CBFbeta chain, and a dna-binding cbfalpha gene (RUNX1, 2, 3)

CBFbeta does not bind DNA, it allosterically enhances DNA binding by the cbfalpha subunit

Question 23

Draw a picture of CBFb and RUNX1 for dna

Answer 23

CBFbeta
Runx1
DNA
leads to transcription of target genes which activate or suppress transcription

Question 24

What is the cytogenetic abnormality associated with AML M2? What is the prognosis of this?

Answer 24

t(8;21)(q21;q22)
this leads to RUNX1T1 mutation.
it disrupts maturation due to binding to CBFalpha on DNA
It confers a low risk, so good overall prognosis

Question 25

What is the mutation associated with AML M4 Eo?

What is its prognosis?

Answer 25

Inversion 16
this confers good prognosis and low risk
This inversion leads to incomplete transcripts for the CBFbeta gene, it is fused with MYH11, this means it leads to maturation arrest

Question 26

Which mutations occur in t-AML and what is there prognosis?

Answer 26

inv(3) - leads to high risk AML, GATA2 distal enhancer is brought in close proximity to EVI1 gene leading to leukaemogenesis

Question 27

What is another mutation with poor outcome?

Answer 27

11q23, this causes KMT2A disruption, has terrible prognosis

Question 28

List the AML cytogenetics in low, intermediate and high risk

Answer 28

low:
t(15;17)
t(8;21)
inv(16)

Intermediate
Normal karyotype
t(9;11)

High Risk
inv(3)
Complex karyotype

Question 29

Describe the 2 hit hypothesis of AML, who proposed?

Answer 29

Class I mutations: FLT3-ITD, FLT3-TKD, KIT, RAS, JAK2

Class II mutations - PML RARA, RUNX1-RUNX1T1 etc

Class I cause proliferation/survival advantage
Class II cause impaired differentiation and apoptosis
both lead to AML

Gilliland et al 2008