L23 – Leukaemias: Principles of management and diagnosis Flashcards
Define acute leukaemia?
Clonal haematological disorder of precursor myeloid/lymphoid cell origin
≥ 20% leukaemic blasts in the bone marrow or peripheral blood
4 major genetic mechanisms of leukaemogenesis?
- Transcription dysregulation and differentiation block
- Activation of proto-oncogenes
- Inactivation of tumour-suppressor genes
- Activation of signalling genes or receptor tyrosine kinases
List some common genetic mutations in acute leukaemia?
- RUNX1-RUNX1T1** : fusion t(8;21)(q22;q21)
- PML-RARα** :
- TP53 mutation
- CBCF-MYH11 **: t(16;16)
- Various chromosomal translocations
these 3 genetic mutations can classify AML even if <20% blast in PB/BM
Mechanism of RUNx1-RUNX1T1 in acute leukaemia.
Fusion of RUNX1 from chromosome 21 + RUNX1T1 from chr. 8
RUNX1 codes for CBFa transcription factor
RUNX1T1 binds to CBFa and disrupt connection with co-activator»_space; cannot start transcription of target gene
Mechanism of CBFβ-MYH11
in acute leukaemia.
MYH11 binds to CBFβ transcription factor»_space; block co-activators from binding to CBFβ»_space; block transcription of target gene
Classify AML into 5 classes?
- AML with recurrent genetic abnormalities
- AML with myelodysplasia-related changes/ after MDS
- Therapy-related myeloid neoplasm/ AML
- Myeloid sarcoma (isolated myeloid sarcoma is rare)
- Miscellaneous types with diff. morphology
What is the concurrent condition of isolated myeloid sarcoma?
AML
rarely exists alone
List the 3 mutations used to classify AML?
t(8;21)»_space; RUNX1-RUNX1T1
inv(16) or t(16;16)»_space; CBCF-MYH11
APL with PML-RARA
Genetic mutation that marks APL?
PML-RARα
List 2 Precursor lymphoid neoplasms.
- B-ALL & B-lymphoblastic lymphoma
* T-ALL & T-lymphoblastic lymphoma
Walk through sequence of investigations for acute leukemias?
1) Specific diagnosis
2) Detect and predict disease complications + prognosis
3) Determine fitness for treatment
4) Detect treatment response and complications
List 4 blood metrics* checked for Acute leukaemia.
- CBC with manual review and differential count
- Clotting profile, d-dimer and fibrinogen (check for DIC, esp. for APL)
- Serum electrolytes (Na, K, Ca, PO4)
- LDH and urate levels (Tumor lysis syndrome)
List 4 tests for fitness for chemotherapy treatment in acute leukemia?
Liver, lung and renal function tests
ECG and transthoracic echocardiogram (anthracycline, cardiotoxicity)
HBV, HCV, HIV serology
G6PD assay (oxidative hemolysis with Co-trimoxazole)
Which tests give diagnositic and prognostic indicators for acute leukemia?
bone marrow aspiration and trephine biopsy
Cytogenetic e.g. FISH
Which investigation is used to delineate AML from ALL?
Cytochemistry with Myeloperoixdase and Sudan black B»_space; specific for myeloid lineage
Which investigation is used to SUBCLASSIFY lineages of AML and ALL?
Flow cytometry
best for finding concurrent CD antigens
Which investigations for finding chromosomal/ genetic abnormalities in AML/ ALL?
Molecular genetics (PCR based)
Cytogenetics: Karyotype and FISH
Which investigation for identifying morphology of leukaemic cells?
Peripheral blood smear
BM biopsy exam