AML Flashcards
Give a brief background of AML
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
What is the aetiology of AML?
External risk factors: Benzene - primarily found in gasoline and by-products Car fumes Smoking Exposure to radiations
What are some factors that can contribute to AML?
Age
Familiar types
Previous treatment for cancer - treatment-related AML
Describe the presenting symptoms of AML
Tiredness Bruising and bleeding Shortness of Breath Weight Loss Infections
How is diagnosis of AML made?
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
How is AML classified?
FAB classification AML Mo AML M1 AML M2 AML M3 - apml AML M4 - eo type AML M5 AML M6 AML M7
Where do the leukaemias arise?
AML M0 - M5 occur in the bone marrow
AMLM6 and M7 occur in the peripheral blood
Describe the appearance of AML M0 and M1 on the blood film
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
How do you tell the difference between AML and ALL on the blood film?
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
What is the significance of auer rod findings?
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
What is seen in the morphology of M4 with eosinophilia?
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
What is seen in the morphology of AML M5?
Leukaemia which classically presents with gum hypertrophy
Monocytes have a kidney shaped nucleus
How are the granules in myeloid cells exploited for identification?
The granules are absent in lymphoid cells so you can stain for myeloperoxidase which is contained in the granules
Which stains are AML positive for?
MPO and sudan Black
Describe the flow cytometry for AML
CD13 CD33 myeloid markers CD34 - early precursor marker HLA-DR - also immature myeloid marker CD11c - myeloid marker CD117 - Early Myeloid marker
What is particular about AML M0?
It is negative for all differentiation markers - MPO, CD117, CD33 apart from CD34 and HLA-dr
What is seen in AML M1 and M2?
CD117 CD13, and CD33
and CD34 and HLA-DR
What flow cytometry is seen in AML M4?
CD34, CD117, Cd13 and CD33
and CD16 and CD64 for monocytic differentiation
What is the intermediate risk group?
Everything in between, so normal karyotype or cytogenetics abnormalities not included in other categories, being over the age of 60
Describe a study which investigates the prognosis difference between younger and elderly patients
Applebaum et al 2005 found that:
Drug resistance: <56: 33% >75:57%
Favourable cytogenetics <56: 17% >75:4%
Unfavourable cytogenetics: <56: 35%, >75: 51%
What family of genes are affected in AML?
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
Which study investigated the CBF? What is the importance of CBFbeta?
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
Draw a picture of CBFb and RUNX1 for dna
CBFbeta
Runx1
DNA
leads to transcription of target genes which activate or suppress transcription
What is the cytogenetic abnormality associated with AML M2? What is the prognosis of this?
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
What is the mutation associated with AML M4 Eo?
What is its prognosis?
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
Which mutations occur in t-AML and what is there prognosis?
inv(3) - leads to high risk AML, GATA2 distal enhancer is brought in close proximity to EVI1 gene leading to leukaemogenesis
What is another mutation with poor outcome?
11q23, this causes KMT2A disruption, has terrible prognosis
List the AML cytogenetics in low, intermediate and high risk
low:
t(15;17)
t(8;21)
inv(16)
Intermediate
Normal karyotype
t(9;11)
High Risk
inv(3)
Complex karyotype
Describe the 2 hit hypothesis of AML, who proposed?
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
