HIS23 Acute Leukaemia: Principles Of Diagnosis And Management

Question 1

Acute leukaemia

Answer 1

• Clonal haematological disorder of ***precursor Myeloid / Lymphoid cell origin (i.e. reside in BM)
• > =20% blasts in BM/PB (except in specific entities of AML with recurrent cytogenetic abnormalities)
• rapidly progressive, fatal if left untreated
• diagnosis require integration of
  —> Clinical presentation
  —> Morphologic (BM aspirate, Trephine biopsy)
  —> Immunophenotypic (myeloid / lymphoid origin)
  —> Genetic information (classification —> pathogenesis, prognosis, therapy)

Question 2

4 Major genetic mechanisms of leukaemogenesis

Answer 2

1. Transcription dysregulation and differentiation block (cell proximal to block will proliferate)
2. Activation of proto-oncogenes (cellular proliferation, inhibited apoptosis)
3. Inactivation of tumour-suppressor genes
4. Activation of signalling genes / receptor tyrosine kinases

They occurs via:

• Chromosomal translocations
• Deletions
• Duplications / Amplifications
• Point mutations
• Epigenetic alterations (pathways that regulate gene expression)

Question 3

Acute Promyelocytic Leukaemia

Answer 3

Subtype of AML

—> t(15;17)(q22;21)/PML-RARa

Question 4

AML

Answer 4

Apart from morphological classification
—> also classified based on genetic information
—> pathogenesis, prognosis, therapy

Therefore, all AML require cytogenetics and molecular assessment

Question 5

Core-binding factor leukaemias: Chromosomal translocation

Answer 5

CBFα (RUNX1) + CBFβ + Coactivators (required for transcription of genes for normal haematopoiesis)

1. AML with t(8;21)(q22;q21); ***RUNX1-RUNX1T1 (fusion gene)
   - RUNX1T1 (chromosome 8) binds to CBFα
   —> disrupt binding of CBFα (chromosome 21) to Coactivator
   —> gene transcription blocked
   —> abnormal cell proliferation
2. AML with inv(16)(p13.1q22) / t(16;16)(p13.1;q22); ***CBFβ-MYH11 (fusion gene)
   - MYH11 binds to CBFβ
   —> MYH11 blocks CBFβ binding to Coactivator
   —> gene transcription blocked
   —> abnormal cell proliferation

Question 6

Only Acute leukaemia / precursor neoplasms that need to know

Answer 6

1. Acute myeloid leukaemia
2. Acute lymphoblastic leukaemia
   - B-ALL (lymphoma as LN involvement, but still acute since “blastic”)
   - T-ALL (lymphoma as may have mediastinal mass, but still acute since “blastic”)

Question 7

Acute myeloid leukaemia

Answer 7

Classification (x rmb):

• AML with recurrent genetic abnormalities
• AML with MDS changes
• Therapy-related myeloid neoplasm / therapy-related AML (i.e. secondary to chemotherapy)
• AML, not otherwise specified (not belong to above 3 categories —> diagnosis based on morphology ~ FAB classification)
• Myeloid sarcoma (isolated myeloid sarcoma is rare, usually occurs in association with pre-existing AML)

Question 8

AML with recurrent genetic abnormalities

Answer 8

Most important 3:

1. ***Acute Promyelocytic leukaemia with PML-RARA (fusion gene)
2. AML with t(8;21)(q22;q21); RUNX1-RUNX1T1
3. AML with inv(16)(p13.1q22) / t(16;16)(p13.1;q22); CBFβ-MYH11

***All above can be classified as AML even with blasts <20% in PB/BM

Question 9

Aims of investigations in acute leukaemia

Answer 9

1. Specific diagnosis
2. Disease complications
3. Prognosis (using cytogenetics markers)
4. Fitness for treatment
5. Treatment complications
6. Response to treatment

Question 10

***Investigations in acute leukaemia

Answer 10

1. CBC with manual blood film review + differential count (D/C)
   (- low Hb, low platelet)
2. ***Clotting profile, d-dimer, fibrinogen (比Lymphoma多左呢樣)
   - essential in all subtypes in acute leukaemia —> DIC —> bleeding tendency
3. Diagnostic BM aspiration, Trephine biopsy
   - cytogenetics, molecular assessment with BM aspiration
   - confirm diagnosis
4. CXR
   - look for disease complications, active / prior infections (e.g. TB)
5. LFT, RFT
   - infiltration of liver, tumour lysis syndrome affect RFT, baseline impairment that affects treatment
6. Serum electrolytes
   - Na, **K, Ca, **PO4 —> ↑ in tumour lysis syndrome
7. LDH, urate levels
   - tumour lysis syndrome

Diagnostic:

• **BM examination:
  1. Morphology on PB/BM —> APL, AML, ALL
  2. Cytochemistry (MPO, SBB) —> AML vs ALL
  3. Immunophenotype (Flow cytometry) —> for subclassification lineage specification (B-ALL vs T-ALL)
  4. Cytogenetics (and FISH to detect specific chromosomal abnormalities) —> diagnosis and prognosis
  5. Molecular genetics —> diagnosis and prognosis (e.g. RT-PCR to detect PML-RARA for APL)

Further other investigations:
1. ECG, transthoracic echocardiogram (cardiotoxicity with Anthracyclines)
(Lung function no need —> Bleomycin only for Lymphoma)
2. Hepatitis B, C serology (risk of reactivation)
3. HIV serology (risk of reactivation, more related to lymphoma)
4. G6PD assay (oxidative haemolysis with Co-trimoxazole)
5. HLA-typing of patients, siblings for allogeneic HSCT (unrelated donors search if siblings not HLA indentical)

Question 11

Principles of management of Acute leukaemia

Answer 11

1. Induction of remission
   - chemotherapy to achieve morphologic remission:
   —> maximal cell death
   —> <5% blasts in BM
   —> recovery of other cell lineages
2. Consolidation of remission
   - clear up microscopic disease
3. Maintenance of remission
   - only for APL and ALL
   —> reduce risk of relapse with prolonged treatment
   —> aim to eradicate microscopic disease
4. Allogeneic HSCT in selected patients (with high risk of disease)

General indications (x rmb):
AML:
- High risk AML (based on cytogenetics / genetic changes) in first remission
- Relapsed AML achieving second remission

ALL:

• High risk ALL (based on cytogenetics / genetic changes) in first remission
• Persistent of measurable residual disease (MRD) in first remission
• Relapsed ALL achieving second remission

Question 12

Case 1:

• 52 yo
• non-smoker, non-drinker, good past health
• no family history of malignancy
• fever, SOB for 2 weeks
• pallor
• no palpable LN / hepatosplenomegaly
• CVS/Resp/CNS system unremarkable
• Fundoscopy: mildly engorged retinal veins —> hyper viscosity
• CBC: Hb 6.5, WBC 540.95, Platelet 62

Answer 12

Mildly engorged retinal veins —> hyper-viscosity due to ***hyperleukostasis
Hb: 6.5 (~13) —> low
WBC: 540.95 (4-10) —> high
Platelet: 62 (150-450) —> low

Investigation required:

1. CBC with blood film review + D/C —> 78% leukaemic blasts (medium in size without granules / Auer rods)
2. Clotting profile and fibrinogen —> Normal
3. LRFT, electrolytes —> Normal
4. LDH 1200 —> High (∵ high cell turnover)
5. CXR —> Increased lung markings —> ***Hyperleukostasis —> Leukocyte infiltration into pulmonary vessels

Without granules + Without Auer rods —> ***Lymphoblasts
(With granules / Auer rods: suggest Myeloid lineage)

Treatment:
Urgent management
1. IV fluid + Febuxostat —> prevent tumour lysis syndrome + protect kidneys
2. Urgent chemotherapy —> temporary cytoreduction given in view of symptomatic hyperleukostasis

Diagnostic investigation:

1. BM aspirate —> 96% blasts
2. MPO, SBB —> -ve stain —> suggest lymphoid lineage
3. Flow cytometry —> early precursor B cell immunophenotype (CD19+, CD79a+, CD22+, weak CD34+, CD10 + Cytoplasmic μ chain -ve)
4. Karyotype —> t(4;11)(q21;q23)
5. FISH confirmed KMT2A-AFF1 fusion

Final diagnosis: B-ALL

Further investigations:

1. ECG, echocardiogram —> Normal
2. Hep B, C, HIV —> -ve

Treatment:

1. Induction chemotherapy:
   - Doxorubicin
   - Vincristine
   - Corticosteroids —> lympholytic
   - L-asparaginase —> lympholytic
2. CNS prophylaxis —> tendency to leptomeningeal spread —> Intrathecal methotrexate
3. Consolidation of remission
4. Maintenance of remission
5. Planned for allogeneic HSCT in view of high risk B-ALL by karyotype
6. 2 siblings not HLA identical —> HSCT from matched unrelated donor

Question 13

***Practical approach to high WBC count

Answer 13

High WBC —>

1. Clonal
   - Blasts >20% —> AML / ALL
   - Blasts <20% —> Other myeloid malignancy (MDS, MPN, CMML)
   - No leukaemic blasts but abnormal lymphoid cells present (e.g. B-CLL)
2. Reactive (“Leukaemoid”) —> ***BUT won’t be sky high (rarely >50)
   - search for underlying cause
   —> infection
   —> inflammatory / autoimmune
   —> paraneoplastic
   —> reactive to solid organ tumours

Question 14

Case 2:

• 37 yo mechanic
• chronic smoker
• good past health
• spontaneous gum bleeding, easy bruising for 1 week
• pallor
• generalised petechiae, bruises
• mild hepatomegaly
• no splenomegaly
• fundoscopy: no retinal haemorrhage
• Hb 6.5
• WBC 6.55
• Platelet 16

Answer 14

• Hb 6.5 —> low
• Platelet 16 —> low

Investigation required:

1. CBC with blood film review + D/C —> No abnormal Promyelocytes, 36% medium to large blasts with granules, D/C showed absolute neutropenia of 0.8
2. Clotting profile and fibrinogen —> Normal
3. LRFT, electrolytes —> Normal
4. LDH 1041 —> High (∵ high cell turnover)
5. CXR —> Normal

With granules: suggest Myeloid lineage

Treatment:
Urgent management
1. IV fluid + Febuxostat —> prevent tumour lysis syndrome + protect kidneys
2. Urgent chemotherapy NOT needed —> WBC not high (<100) + without symptoms of hyperleukostasis

Diagnostic investigation:

1. BM aspirate —> abnormal leukaemic blasts with granules
2. Karyotype —> t(9;11)(p21.2;q23.3) —> poor prognosis

Final diagnosis: AML

Further investigations:

1. ECG, echocardiogram —> Normal
2. Hep B, C, HIV —> -ve
3. One sibling HLA identical

Treatment:

1. Induction chemotherapy (“3+7” induction):
   - Daunorubicin (3 days)
   - Cytarabine (7 days) —> Antimetabolite
2. Consolidation chemotherapy with 4 cycles of high-does Cytarabine
3. Planned for allogeneic HSCT in view of high risk AML in CR1 —> HSCT from matched sibling