6: Abnormal White Cell count

Question 1

Leucocytosis:
1. Explain how to analyse the cause of a leucocytosis (differential count / blood film)

2. List the common causes of a neutrophilia, eosinophilia and lymphocytosis
3. Explain how a reactive polyclonal response may be differentiated from a lymphoproliferative disorder

Answer 1

?

Question 2

Which cytokines are important for differentiation/proliferation of RBCs, lymphocytes and myeloid cells?

Answer 2

RBCs = EPO
Lymphocytes = interleukin IL-2
Myeloid = G-CSF and M-CSF (growth factors)

Question 3

What are causes of decreased white cell production?

Answer 3

Impaired bone marrow function

Due to B12 or folic acid deficiency
or bone marrow FAILURE (cancer/chemo)

Question 4

How do you investigate raised WCC?

Answer 4

Clinical history + examination
Hb + platelet count
Automated differential
Examine blood film

Question 5

What questions should be asked about the blood film?

Answer 5

What cell lines are affected
Which WC lines are affected
Are the WCs mature or immature?

Question 6

What are mature/immature WCs associated with?

Answer 6

Mature + all lineages = Reactive OR CLL if monoclonal

Mature + immature = Chronic myeloid leukemia (mature neutrophils)

Immature only + low Hb/platelets = Acute leukemia

Question 7

Common causes of reactive/malignant neutrophilia

Answer 7

Reactive:
Infection
Tissue inflammation (e.g. pancreatitis, colitis)
Corticosteroids, physical stress, adrenaline
Underlying neoplasia

Malignant:
Myeloproliferative disorders
Chronic myeloid leukemia

Question 8

Common causes of reactive/malignant eosinophilia

Answer 8

Reactive:
Parasytic infestation
Allergic autoimmune disorder (asthma)
Hypereosinophilic syndrome
Neoplasia

Malignant:
Lymphoma (Hodgkin’s or T-cell NHL)
Chronic eosinophilic leukemia

Question 9

How do you distinguish types of lymphocytosis?

Answer 9

Mature cells = REACTIVE if polyclonal, CLL if monoclonal

Immature cells = Acute Lymphoblastic leukemia

Question 10

With MATURE cells, how do you distinguish whether it is primary (malignant) or reactive?

Answer 10

Reactive -> Polyclonal (cells look DIFFERENT)

Primary (malignant) -> MONOCLONAL (cells look the same) occurs in CLL

Question 11

Describe what Acute lymphoblastic leukemia looks on a blood film

Answer 11

Twice the size of normal lymphocytes

Nucleolus visible within cell

Question 12

Causes of reactive lymphocytosis?

Answer 12

Infection (EBV)
Infectious hepatitis, rubella, herpes
Autoimmune disorders
Neoplasia
Sarcoidosis

Question 13

What is the result of an EBV infection?

Answer 13

Glandular fever

Question 14

What are tests to distinguish between reactive and malignant lymphocytosis?

Answer 14

1. Look at FBC - Low Hb/platelet + increased WCC suggests ALL
2. Look at morphology on blood film: are the cells same or different shaped?

Mature + polyclonal = Reactive
Mature AND Immature = Chronic MYELOID leukemia

Malignant:

• Mature + MONOCLONAL = CLL
• Immature = Lymphoma/Leukemia (e.g. Acute lymphoblastic leukemia)

Mature AND Immature = Chronic MYELOID leukemia

2. Confirm if it is mono/polyclonal using Peripheral blood Immunophenotype - B cell light chain reaction

Kappa or lambda ONLY = MONOCLONAL = MALIGNANT
Both kappa AND lambda = POLYCLONAL = Reactive

Question 15

What lab results would be seen in chronic lymphocytic leukemia?

Answer 15

CLL = monoclonal AND mature cells

Peripheral blood immunophenotype:
kappa or lambda ONLY

Question 16

How do you confirm if it is a reactive lymphocytosis or CLL?

Answer 16

Reactive = polyclonal cells
CLL = monoclonal cells

Use peripheral blood immunophenotype test
(B cell light chain reaction)

If both kappa AND lambda chains present, it is POLYCLONAL therefore REACTIVE

If only kappa/only lambda present, it is MONOCLONAL therefore CLL