Leukaemia

Question 1

What is leukaemia?

Answer 1

• A neoplastic condition of the blood and/or bone marrow in which neoplastic cells of lymphoid or non-lymphoid stem cells or their progeny undergo clonal expansion with or without cellular differentiation (BSAVA Manual of Vet Clin Path)
• Leucocytosis/high numbers of leukaemic cells in circulation
• Leukaemic cells may infiltrate tissues (e.g., liver, spleen, lymph nodes)

Question 2

What causes clinical signs in leukaemia?

Answer 2

◦ Failure of normal marrow function
◦ Infiltrated organ dysfunction
◦ Hyperviscosity
◦ Paraneoplastic syndromes (IMHA, hypercalcaemia)

Question 3

When should you suspect leukaemia?

Answer 3

• Unspecific clinical signs (e.g., lethargy, anorexia, weight loss) + CBC showing severe leucocytosis (>100,000/μL)
• Atypical cells on blood smear review
• Persistent lymphadenomegaly
• Persistent cytopenias
• Splenomegaly and/or hepatomegaly
• Persistent hyperglobulinaemia -> serum protein electrophoresis
• Persistent hypercalcaemia -> ionised calcium
• Incidental finding of severe and/or persistent leucocytosis

Question 4

What are the 2 types of leukaemia?

Answer 4

• acute
• chronic

Question 5

What are the characteristics of acute leukaemia?

Answer 5

• Neoplastic transformation during stem cell proliferation
• Large numbers of immature (undifferentiated) cells
• Aggressive rapid disease
• Cytopenia is very common
  ◦ Marrow disruption by neoplastic expansion
  ◦ E.g., neutropenia, thrombocytopenia, anaemia

Question 6

What are the characteristics of chronic leukaemia?

Answer 6

• Neoplastic transformation following differentiation
• Giving rise to large numbers of mature (differentiated) cells
• Slow progression and less aggressive in comparison to acute disease
• Cytopenia is rare

Question 7

What can i do in first opinion practice when suspecting leukaemia?

Answer 7

• Diagnose leukaemia (acute vs chronic)
  ◦ Blood smear examination
• Diagnose lymphoma
  ◦ Lymph node cytology
• Exclude other causes of leucocytosis (e.g., infectious)
• Refer to oncology

Question 8

What are the 2 types of chronic leukaemias?

Answer 8

• myeloid
• lymphoid

Question 9

What are the characteristics of the leukaemic phase of lymphoma?

Answer 9

• Originates outside the bone marrow (extramedullary)
• Document lymphoma in periphery (e.g., lymph nodes, spleen, liver)
• In the leukaemic phase (stage V) there are lymphoma cells in the blood and/or bone marrow
• No or mild cytopenias
• Bone marrow infiltration usually <25%
• Better prognosis than acute leukaemia
• The neoplastic cells are lymphocytes!