Haematological malignancy

Question 1

How is haematological malignancy classified via morphology

Answer 1

• Morphology = what it looks like
• Bloodm bone marrow or lymphoid tissue - diagnostic and other tests back it up
• Can be used for screening

Acute promyelocytic leukaemia (subtype of AML) - Large cells, abundant cytoplasm

Hairy cell leukaemia- Chronic B lymphocytic leukaemia - single large cell with hair like projections

Question 2

How are haematological malignancies classified via immunophenotype

Answer 2

• Antigen expression on cell surface and intracellularly
• Checked by flow cytometry
• Forward scatter= cell size
• Side scatter= cell complexity and granularity of cytoplasm
• Fluorsecence= surface/ cytoplasmic antigen expression

-Can tell number of cells positive for an antigen and intensity of an antigen expression on a cell

• Antibody panels look at cell type - myeloid/ lymphoid
  - If lymphoid they look at B/T/NK
  - Stage of differentiation

Question 3

What are the common leukocyte antigens in these haematological cancers

• Acute lymphoblastic leukaemia
• Acute myeloid leukaemia
• Chronic lymphocytic leukaemia

Answer 3

• ALL- lymphoblasts
• AML- Myeloblasts
• CLL- Lymphocytes

Question 4

How are haematological malignancies investigated via cytogenetics

Answer 4

1. Culture cells from bone marrow and promote mitosis
2. Stop cell division at metaphase
3. Giemsa staining- banding patterns along chromatids
4. High power microscope looks at karyotype for numerical and structural abnormalities

FISH- flurosecence in situ hybridisation

    - Detects specific DNA sequences in a target genome 
    - 2 types - chromosome paints or locus probes

Question 5

What are the genetic features of acute promyelocytic leukaemia

Answer 5

-Translocation between long arm Chr 15 and Chr 17 creating PML RARA gene

Question 6

What are the genetic features of acute myeloid leukaemia

Answer 6

• Loss of long arm on chromosome 15
• Abnormalities of Chr 5, 11, 15, 17 , loss of 1 copy of Chr 8
• Multiple abnormalities- complex karyotype= poor prognosis

Question 7

What method is used to investigate molecular genetics and when is it indicated

Answer 7

PCR- DNA amplified to produce thousands of copies of same sequence
-DNA target sequence is denatured and separated DNA stands then annealed to primers and extended by taq polymerase

Indications

• CML and philadelphia positive ALL - detects the BCR- ABL1 fusion gene
• Molecular monitoring for residue or re-emergence of disease
• Myeloproliferative neoplasms- JAK2 V617F
• Prognosis of AML - presence of FLT3 and NPM mutations
• Assessing clonality of lymphoid proliferations

Question 8

Discuss the features of chronic myeloid leukaemia

Answer 8

• Defined by the presence of the philadelphia chromosome
• Reciprocal translation between long arms of chromosome 9 and 22
• ABL1 oncogene on 9 translocated to BCR point on Chr 22
• Forms BCR-ABL1 fusion oncogene
• Abnormal gene targeted by specific inhibitors - tyrosine kinase inhibitors- imatinib

Patient management: Tyrosine Kinase inhibitors - Imatinib 400mg/ day and monitor response