Leukaemia

Question 1

How does Leukaemia differ from other cancers?

Answer 1

• Leukaemia is a cancer where there is often not a solid tumour, rather the replacement of normal bone marrow cells with leukaemic cells.
• Most common cancers in men and women aged 15-24
• Main cause of cancer death in people aged 1-34

Question 2

How can Leukaemia be classified? What is the cell Lineage?

Answer 2

• Leukaemias that behave in a ‘benign’ manner are called chronic
• Leukaemias that behave in a ‘malignant’, aggressive manner are called acute

Lineage

• Lymphoid
  
  • B or T
• Myeloid
  
  • Granulocytic
  • Monocytic
  • Erythroid
  • Megakaryocytic

1. Acute lymphoblastic leukaemia (ALL)
2. Acute myeloid leukaemia (AML)
3. Chronic lymphocytic leukaemia (CLL)
4. Chronic myeloid leukaemia (CML)

Question 3

What is the difference between Myeloid and Lymphoid Leukaemia?

Answer 3

Myeloid Leukaemia

In acute, the cells continue to proliferate despite being no longer mature so very FEW end cells

• The responsible mutation is usually in a transcription factor – affecting multiple genes.

In chronic, the cells become independent of external signals and reduced apoptosis so MANY end cells

• In chronic the mutation is usually in a gene involved in a signalling pathway, e.g. a membrane receptor or cytoplasmic protein

Lymphoid leukaemia

• Acute has an increase in lymphoblasts with a failure to form mature B and T cells
• Chronic has an increase in mature (but abnormal) T/B cells.

Question 4

What are the Genetic features of ALL, what is the common clinical presentation?

Answer 4

Genetic features:

• Hyperdiploidy – extra copies of multiple chromosomes, this is an example of a leukaemia with a good prognosis
• t(4;11) – This is a poor prognosis
• t(12;21) – A good prognosis – the translocations result in chromosomes that do not look any different so this requires FISH to analyse.

Clinical features:

1. Bone pain
2. Hepatomegaly
3. Splenomegaly
4. Lymphadenopathy
5. Testicular enlargement – Due to infiltration of testes by lymphoblasts
6. Thymic enlargement

Crowding out of normal cells resulting in

1. Fatigue, lethargy, pallor, breathlessness
   
   • Anaemia
2. Fever and other features of infection
   
   • Neutropenia
3. Bruising, petechiae, bleeding
   
   • Thrombocytopenia