Acute Myelogenous Leukemias Flashcards
What are some general features
of AML?
- most adult and infantile leukemias are myeloid
- only 10% of leukemias in children are myeloid
- median age is 65
- AML usually presents with a very high WBC and abundant circulating blasts
- sometimes will present with a soft tissue mass
- chloroma, myeloid sarcoma
How is the diagnosis of
AML made?
- 2 ways to arrive at the diagnosis:
- blast >20%
- < 20% blasts if there is a myeloid sarcoma or characteristic genetic abnormalities
How many cells must be counted
in order to determine blast percentage?
- Bone marrow: 500 cells
- Peripheral blood: 200 cells
Note: in APML, promyelocytes are included in the blast percentage while in Monocytic leukemia promonocytes are included
What is the classic immunophenotype seen
for AML by Flow cytometry?
- CD34
- CD13, CD33
- HLA-DR
- CD45
IMP: APL usually negative for HLA-DR and CD34
** negative for lymphoid markers but some may express CD7 and CD19
What is the gene that is coded
for in AML with t(8;21)(q22;q22)?
- RUNX1 gene
- encodes the alpha chain of core binding factor (CBFa)
- represents 8-10% of de novo AML
- affects young adults and is relatively chemosensitive
What is the morphology of the
blasts in AML with t(8;21)?
- pronounced azurophilic granules
- sometimes large pseudo-Chediak Higashi granules and Auer rods
- Dysplastic mature granulocytes are present in the blood and bone marrow
- display pseudo-Pelger-Huet nuclei with homogeneous pink cytoplasm
What marker, when positive by flow,
should make you consider AML with t(8;21)?
- CD19
- it’s expression should make you consider AML with t(8;21)
What immunomarker expression by
flow should suggest monoblasts?
- expression of CD33 and CD11b
In AML with t(8;21) what is associated
with a poor prognosis ?
- lack of or decreased expression of CD19
- with retention of CD56 expression
- this correlates with a KIT mutation
- poor prognosis
What is the gene that is coded for
in AML inv (16)(p13q22) or
t(16;16)(p13;q22)?
- it is a translocation resulting in the apposition of the MYH11 (myosin) and CBFB genes
- affects younger adults
- relatively chemosensitive
What is the morphology of the blasts in
AML with inv(16) or t(16;16)?
- myelomonocytic differentiation
- usually found in association with eosinophils
- eosinophils usually have abnormal granules that look basophilic (eos-basos)
- stain + with Naphthyl acetate esterase
- this stain is negative in normal eosinophils
What is the immunophenotype of
AML with inv(16) or t(16;16)?
- CD13, CD33
- CD14, CD64
- CD11b, HLA-DR, lysozyme
- also can express CD2
What is the morphology and prognosis for
AML with inv(3) or t(3;3) ?
- genes involved: GATA2-MECOM
- can occur de novo or following MDS
- morphology:
- blasts seen in association with dysmorphic, small, hypolobated megakaryocytes
What is the clinical presentation of
AML t(15;17)(q22;q21)?
- tendency to present in DIC and highly responsive to ATRA
- bimodal distribution
- late teen years and over age 60
What is the morphology of the blasts
for APL?
- abnormal promyelocytes with kidney shaped or bilobed nuclei
- cytoplasm varying from intensely granulated to agranular (microgranular variant)
- microgranular variant can resemble acute monocytic leukemia
- MPO reaction is quite strong in both variants
- weak or negative in monoblasts
How do the hyper and hypogranular
variants present in peripheral blood?
- Hypergranular variant
- very few leukemic cells
- Hypogranular variant
- presents with a high blast count in blood
What is the immunohistochemical finding
for APL?
- Positive:
- CD33, CD13 (both strong)
- CD15 (weak)
- normal promyelocytes will be CD15 strong +
- Negative:
- HLADR and CD34
- Note: these markers can be positive in the hypo/microgranular variant
- also CD2
What are the translocation variants of
APL that are resistant to ATRA?
- t(11;17)
- t(5;17)
What are the three major RARa
breakpoints (for APL)?
- bcr1 - located within intron 6
- bcr2- (exon 6)
- bcr3- (intron 3)
- bcr 3 may have microgranular features
What is Differentiation Syndrome
in APL?
- called Retinoic acid syndrome
- potentially life threatening complication of treatment with ATRA
- Present with:
- fever, weight gain, anasarca
- effusions, hypotension, renal failure
- Risk correlates with initial WBC > 5 x 10^9
- Dexamethasone treatment can prevent or ameliorate it
What is AML with t(6;9) associated with?
- genes: DEK-NUP214
- there is basophilia and multilineage dysplasia
- often in younger adults and children
What age group is AML t(9;11)(p22;q23)
usually seen in and what genes are involved?
- common in children
- AML with KMT2A (MLL) gene anomalies
- FISH is significantly more sensitive for detection
What is the immunohistochemical profile
for AML with t(9;11)?
- monoblastic FAB M4-M5
- CD4, CD14, CD64
- CD11b and lysozyme
IMP:
- CD34 usually negative
What gene fusion is common in
infants with AML containing the MLL gene?
- t(4;11)
- produces MLL/AF4 gene fusion
What is the prognosis of AML with
t(9;11)?
- usually a poor prognosis
- BUT this AML has a better prognosis than other 11q23 aberrations
What is true about AML with t(9;22)?
- de novo AML with t(9;22)
- p210 BCR-ABL translocation
What is classic about AML
with t(1;22)?
- gene fusion: RBM15-MKL1
- often in infants without trisomy 21
- female predominance
- megakaryoblastic differentiation
- express CD41, CD61 and CD42b
What is true about AML with
mutated NPM1?
- favorable prognosis
- in the absence of FLT3-ITD
- normal cytogenetics
- “cup-shaped” nuclei in the blasts
- often CD34 negative
What is the prognosis for AML with
biallelic CEBPA mutation?
- favorable prognosis
- must have absence of FLT3-ITD
- normal cytogenetics
- often in children and young adults