Lecture 3 -- Leucocyte and Platelet Abnormalities

These flashcards cover key concepts about leucocyte and platelet abnormalities as discussed in the lecture.

Which type of white blood cell is shown in this picture? What are the characteristics of this type of white blood cell?

Eosinophil

• Eosinophilia (Organ-pink granules) in cytoplasm

• Segmented nucleus

Which type of white blood cell is shown in this picture? What are the characteristics of this type of white blood cell?

Neutrophil

• Segmented nucleus

• Clear cytoplasm

What indicates a left shift in neutrophils?

Monocyte

• Vacuoles can be observed in cytoplasm

• Grey cytoplasm

• Biggest among all WBCs

• Various shape of nucleus

Which type of white blood cell is shown in this picture? What are the characteristics of this type of white blood cell?

Basophil

• Looks similar to eosinophils

  • Segmented nucleus

• BUT basophilia = Purple cytoplasm

Which type of white blood cell is shown in this picture? What are the characteristics of this type of white blood cell?

Lymphocyte

• Large, round nucleus

• Thin rim of cytoplasm

• Similar size or slightly bigger than erythrocytes

What may be misclassified as lymphocytes by a haematology analyser, causing a false increase in WBC count?

Nucleated red blood cells

When interpreting leukocytes, which is more useful: total WBC count or differential WBC count?

Differential WBC count

What does a differential WBC count measure?

The percentages of different types of leucocytes in the blood.

How can you calculate the absolute number of a specific leucocyte type?

Multiply the percentage of the leucocyte type by the total WBC count.

What does the term 'toxic changes' refer to in neutrophils?

Morphological alterations indicating inflammation

What toxic changes can be observed in neutrophils?

• Foamy cytoplasm → Vacuoles in cytoplasm

• Diffuse cytoplasmic basophilia → Blue/purple cytoplasm instead of clear

• Döhle bodies → Blue granules in cytoplasm

Which type of white blood cell is shown in this picture? What are the characteristics of this type of white blood cell?

Reactive lymphocytes

• Larger than normal lymphocytes

• Eccentric nucleus(shifted to one side)

• Deeply basophilic (blue) cytoplasm

What are the possible causes of neutrophilia?

• Inflammation

• Excess catecholamines

  • Fear, excitement, exercise

• Excess glucocorticoids

  • Hyperadrenocorticism

  • Steroid administration

• Chronic myeloid leukaemia

What are the causes of neutropenia?

Increased use:

• Severe/overwhelming acute inflammation

Decreased production:

• Bone marrow disorders

  • Myelofibrosis / myelophthisis

• Toxic insult e.g. chemotherapy

• Infections (e.g. FeLV, parvovirus)

What leukocyte changes occur with excess catecholamines?

• Neutrophilia

• Lymphocytosis

• Monocytosis

What leukocyte changes occur with excess glucocorticoids?

• Neutrophilia

• Monocytosis

• Lymphopenia

• Eosinopenia

What are the causes of lymphocytosis?

• Chronic inflammation

• Excess catecholamines

• Hypoadrenocorticism

  • Since hyperadrenocorticism causes lymphopenia

• Lymphoproliferative disease

• Young animals

What are the causes of lymphopenia?

• Acute inflammation/stress

• Excess glucocorticoids

  • Hyperadrenocorticism

• Lymphoma

• Loss of lymphocyte-rich fluid (e.g. chylothorax drainage)

What are the causes of monocytosis?

• Acute or chronic inflammation

• Excess glucocorticoids

  • Hyperadrenocorticism

• Secondary to neutropenia

What are the causes of eosinophilia?

• Allergic reactions

• Parasitic infections

• Eosinophilic inflammatory diseases

  • Eosinophilic bronchopneumonia, Eosinophilic enteritis

• Hypoadrenocorticism

  • Since hyperadrenocorticism causes eosinopenia

What are the causes of basophilia?

• Parasitic infections

• Hypersensitivity reactions

• Neoplasia

What should you check on a haematology analyser if thrombocytopenia is reported?

Platelet clumping

• Can cause false low platelet count

Which breeds may normally show thrombocytopenia?

• Sighthounds

• Cavalier King Charles Spaniels

What are the causes of thrombocytopenia?

• Redistribution: splenomegaly

• Increased consumption: DIC

• Increased destruction: autoimmune disease, neoplasia

• Decreased production: myelophthisis

What are the clinical signs of thrombocytopenia?

• Haematuria

• Epistaxis

• Melaena (Digested blood in faeces)

• Petechiae

• Haematochezia (Blood in faeces)

What does the presence of large platelets in a thrombocytopenic animal indicate?

Active thrombopoiesis (bone marrow response)

Interpretation:

• Bone marrow is functioning → production is intact

• Likely causes:

  • Increased destruction (e.g. immune-mediated)

  • Increased consumption (e.g. DIC)

• Less likely: decreased production

What are the causes of thrombocytosis?

• Splenic contraction

• Post-splenectomy

• Iron deficiency anaemia

• Inflammation