Abnormal white cell count

Question 1

What are the common causes of a neutrophilia?

Answer 1

INFECTION
Tissue inflammation, e.g. colitis, pancreatitis
Physical stress
Adrenaline
Corticosteroids
Underlying neoplasia, e.g. lung cancer
Malignant neutrophilia, e.g. myeloproliferative disorders, CML

Question 2

What are the common causes of an eosinophilia?

Answer 2

1. Reactive:
   a) Parasitic infection
   b) Allergic disease, e.g. asthma, rheumatoid, polyarteritis, pulmonary eosinophylia
   c) Neoplasms, e.g. Hodgkin’s, Non-Hodgkin’s lymphoma
   d) Hypereosinophilic syndrome
2. Malignant chronic eosinophilic leukaemia (PDGFR fusion gene) - incredibly RARE

Question 3

What are the common causes of a lymphocytosis?

Answer 3

1. Secondary (reactive):
   - Polyclonal response to infection, chronic inflammation or underlying malignancy
   - E.g. EBV, CMV, toxoplasma, infectious hepatitis, rubella, herpes, AI disorders, neoplasia, sarcoidosis
2. Primary:
   - Monoclonal lymphoid proliferation, e.g. CLL

Question 4

How do you analyse the cause of a leucocytosis?

Answer 4

1. Differential count:
   - Is it only white cells that are raised? Or all red cells, platelets and white cells?
   - If only white cells, is it only 1 cell type or all lineages?
2. Blood film:
   - Mature cells
   - Immature cells - leukaemia

Question 5

What does the presence of blasts in a blood film and low Hb and low platelets suggest as the cause of a leucocytosis?

Answer 5

Acute leukaemia

Question 6

If only lymphocytes are raised, what are the possible causes of a leucocytosis?

Answer 6

Viral infection

Chronic lymphocytic leukaemia

Question 7

How may a reactive polyclonal response be differentiated from a lymphoproliferative disorder?

Answer 7

1. Blood film - look at lymphocytes
   ALL:
   - Immature lymphoblasts - much larger than normal
   - Can see nucleolus within large nucleus

Reactive polyclonal response (infection) or CLL:

• Cells look similar to each other
• Typical appearance of mature lymphocyte w/big nucleus and little cytoplasm

THEN to distinguish between infection and CLL:

2. Light chain restriction:
   - Infection causes polyclonal response - light chains in antibody can be kappa or lambda, tends to be 50:50
   - CLL: monoclonal expansion tf B cells only producing kappa OR lambda - called kappa or lambda restriction
3. Southern blot analysis to look at gene rearrangement
   - Ig and TCR genes undergo recombination in antigen stimulated B cells or T cells
   - W/primary monoclonal proliferation (CLL), all daughters carry identical configuration of Ig or TCR gene