Acute Leukaemia Flashcards
Definition
Clonal haematopoietic neoplasm characterised by accumulation of malignant white cells in the bone marrow and blood
> 20% blasts in PB or BM
Aggressive clinical course
Aetiology and Epidemiology
De novo
- genetic predisposition e.g. Down’s syndrome, fanconi’s anaemia, bloom syndrome
- previous chemotherapy/ radiation
Secondary to MDS or MPN
Epidemiology
- ALL is common form in children (highest incidence at 3-7 yrs)
- AML at all ages but increasing incidence with age
Clinical presentation of acute leukaemia
BM failure (blasts interfere with normal development)
- anaemia
- thrombocytopenia (bleeding tendency)
- neutropenia (infection)
Hyperleucocytosis (>100)
–> hyperviscosity syndrome –> reduced tissue perfusion and hypoxia
Organ infiltration
- bone pain (ALL)
- lymphadenopathy (ALL)
- testicular swelling (ALL)
- CNS symptoms e.g. headache, blurred vision, SOB (ALL)
- mediastinal mass (T-ALL)
- gum hypertrophy (AML-M5)
Classical presentations of APL
Bleeding tendency!
- Extensive ecchymoses due to DIC, fibrinolysis and thrombocytopenia
- intracranial bleeding
Classification of leukaemia
Myeloid vs Lymphoid
Acute vs Chronic
- acute = accumulation of precursors (blasts
- chronic = accumulation of mature/differentiated cells
Classification of AML
Risk stratification, predict prognosis and formulate management
Classify based on cytogenetic abnormalities, gene mutations, dysplasia, history of therapy
- AML with recurrent genetic abnormalities e.g. inv(16), t(8;21), APL with t(15;17), NPM1 mutation etc
- AML with myelodysplasia related changes e.g. hx of MDS
- therapy related myeloid neoplasms e.g. hx of chemotherapy
- AML not otherwise specified
Classification of ALL
B lymphoblastic vs T lymphoblastic vs ambiguous lineage
for B-ALL
- with recurrent genetic abnormalities e.g. t(9;22), hyperdiploidy
- not otherwise specified
Investigation of acute leukaemia
- CBC, Blood film, BM immunophenotyping –> confirm diagnosis and define Myeloblast vs Lymphoblast
- Cytogenetics (karyotyping, FISH) and genetic analysis –> subtyping, identify markers useful for therapy and monitoring
- Plan appropriate treatment e.g. chemotherapy with ATRA and arsenic trioxide in APL, allogeneic SCT in poor risk groups, molecular targeted therapies
- Look for complications
- profound DIC in APL – PT, APTT, D-dimer, Fibrinogen
- septicaemia – blood culture
- tumour lysis syndrome – RFT, uric acid, Ca, PO4, LDH
- extra-medullary involvement – lumbar puncture (ALL) - Rule out other diseases that may mimic acute leukaemia e.g. AA, marrow infiltration by CA causing B< failure
B-ALL prognostic subgroups
Unfavourable
- <1 yrs old or >10 yrs old
- hypodiploidy, t(9;22)
- MRD >0.01% on day 29
Favourable
- 1-10 yrs old
- hyperdiploidy, t(12;21)
AML prognostic subgroups
Favourable
- APL
- t(8;21), inv(16)
- NPM1/CEBPA mutant
Unfavourable
- inv(3), monosomy 7
- FLT3 mutant
CBC, Blood film and BM in acute leukaemia
CBC
- pancytopenia
- leucocytosis (variable)
Blood film
- circulating blasts (myelo-/lympho-)
- circulating promyelocytes – APL (bi-lobated nuclei, heavily granulated, auer rods; Faggot cells)
- Auer rods
- leucoerythroblastic blood picture
- dysplastic neutrophils (hyposegmented, hypogranular cytoplasm)
BM
- blasts
- hypercellular with diffuse infiltration
- abnormal promyelocytes with auer rods
Myeloblast vs Lymphoblast morphology
Myeloblast
- abundant cytoplasm, fine granules, Auer rods, fine chromatin, prominent nucleoli
Lymphoblast
- very high N:C ratio, agranular cytoplasm, clumped chromatin, indistinct nucleoli
Immunophenotyping - function, method, differentiating markers
Confirm diagnosis and lineage by identification of lineage specific antigens
Fluorochrome labelled Ab specific to cell surface markers –> process by flow cytometry –> scatter plots
B-lymphoblasts: CD10, 19, 22, 34, Tdt (rarely express CD20 which is mature Ag)
T lymphoblasts: CD3, 7, 34, Tdt (early); CD2, 5, 4, 8 (on further differentiation)
- negative for surface CD3 which is expressed late in maturation
Myeloid:
- myeloblast, monoblast: CD34, 117, 13, 33
- erythroblast: CD235a, HbA (and 34, 117)
- megakaryoblast: CD31, 41, 42, 61
Genetic analysis in acute leukaemia - purpose
DNA changes at chromosome level or nucleotide level which can be visualised in cytogenetic analysis or detected by PCR
==> prognostic implication and risk stratification
==> molecular targeted therapy feasibility
==> MRD monitoring
Genetic analysis: cytogenetics - method, example of abnormality
Direct morphological analysis of chromosomes
- tumour cells cultured and arrested at metaphase the condensed
- each chromosome has own specific banding pattern
Look for gain/loss of chromosome
Deletion, duplication, inversion, translocation
e.g. t(15;17) in APL - PML-RARA
Genetic analysis: molecular studies - purpose
Confirm cytogenetic abnormality
Detect small mutations which may have been missed by cytogenetics
*MRD monitoring by q-PCR
e.g. normal karyotype in AML but presence of FLT3-ITD mutation = poorer prognosis but also means that targeted therapy is possible using FLT3 inhibitors
whereas
NPM1 and CEBPA in absence of FLT3 gives favourable outcome
NPM1 and FLT3 mutations in AML
NPM1
- nucleophosmin gene mutation in 35% cases
- exon 12, affect C terminal portion of protein thus altering its subcellular location
- insertion – frameshift
FLT3
- FMS-like tyrosine kinase 3 in 25-30% cases
- TK involved in regulating proliferation of progenitors
- FLT3-ITD (duplication, in-frame) and FLT3-TKD (missense)
- -> ligand independent constitutive activation of FLT3
