Haematology 4 Flashcards
LEUKOCYTE ABNORMALITIES. 1. Leukogram patterns- physiological, stress and inflammatory. 2. Individual leukocyte changes. 3. Neoplasia of the haematopoeitic system.
PHYSIOLOGICAL RESPONSE
Mild mature neutrophilia, lymphocytosis +/- monocytosis.
Seen secondary to epinephrine (adrenaline) release.
Short lived (resolved after 30 minutes).
Seen in young animals (<1 year)
STRESS RESPONSE
Stress leukogram.
Mild to marked mature neutrophilia (up to 2x more than upper reference), lymphopaenia (decreased lymphocytes), eosinopaenia (decreased eosinophils) +/- monocytosis.
Due to exogenous or endogenous corticosteroids.
Neutrophils from bone marrow storage pool and marginated pool move to circulating pool.
Lasts for ~24 hours, longer is steroid exposure is prolonged.
INFLAMMATORY LEUKOGRAM
Mild to marked neutrophilia, lymphopaneia and monocytosis. Presence of LEFT SHIFT or TOXIC CHANGE. Magnitude of change depends on: Duration Severity of inflammation Nature of inflammation Species of animal
LEFT SHIFT
If demand is high, immature leukocytes are released from the bone marrow.
Can be REGENERATIVE or DEGENERATIVE, or a LEUKAEMIOID REACTION.
REGENERATIVE LEFT SHIFT
Neutrophilia with mainly mature neutrophils and some immature forms.
DEGENERATIVE LEFT SHIFT
More immature than mature neutrophils are seen.
Neutrophil count may be normal, mildly raised, or reduced.
LEUKAEMOID REACTION
Very HIGH neutrophil count seen, with left shift (immature forms released)
TOXIC CHANGE
Seen in marked inflammation, especially bacterial infections and marked tissue necrosis.
Due to direct toxic effects on neutrophil progenitors and also due to immaturity of cells being released in to blood.
- Dohle bodies- dark, blue-grey inclusion bodies in neutrophils, though to be endoplasmic reticulum remnants.
- Increased cytoplasmic basophilia (RNA)
- Cytoplasmic vacuolation
- Toxic granulation
- Cell and nucleus swelling
- Giant neutrophils, ring forms (rare)
SPECIES DIFFERENCES
Cats and dogs are capable of marked neutrophilias- more so than horses, which are more capable than ruminants.
cat/dog > horse > ruminant
-Ruminants typically see neutropaenia in the initial stages of inflammation.
-Horses may also see acute neutropaenia, ESPECIALLY in endotoxaemia- endotoxin stimulates margination of neutrophils.
-Peracute, severe, overwhelming inflammation can cause neutropaenias in cats and dogs- uncommon.
NEUTROPHILIA
Increased number of circulating neutrophils.
Occurs with:
-Excitement- physiological (mild)
-Stress/corticosteroids (stress leukogram)
-Inflammation
-RARELY with granulocytic leukaemia.
NEUTROPAENIA
DECREASED number of circulating neutrophils.
Cattle see transient neutropaenia with acute inflammation.
Other species:
-Severe overwhelming inflammation
-Toxic depression of bone marrow (eg. toxins/drugs, infectious agents, neoplasia or myelodysplastic syndromes)
-Immune mediated- rare, controversial.
These causes are clinically important- risk of infection.
EOSINOPHILIA
Increased number of circulating eosinophils.
Occurs in response to IL-5 release from T cells and histamine release from Mast cells.
Seen most commonly in PARASITIC CONDITIONS and ALLERGY/HYPERSENSITIVITY.
-Paraneoplastic eosinophilia is uncommon- Mast cell disease, lymphoma, various other neoplasms (rare)
EOSINOPAENIA
Decrease in circulating eosinophils.
Endogenous and exogenous steroids inhibit Mast cell granulation and neutralise histamine, thus decreasing IL-5 release and eosinophil release.
By itself, eosinopaenia is of little diagnostic significance.
MONOCYTOSIS
Increase in circulating monocytes.
- Excitement/physiological- mild, mature.
- Stress/exogenous corticosteroids (dogs)
- Inflammation- marked
- Monocytic leukaemia- rare.
MONOCYTOPAENIA
NOT RECOGNISED- reference interval is close to zero.
LYMPHOCYTOSIS
Increase in circulating lymphocytes.
- Physiological (excitement)
- May occur in infectious disease during recovery, or in chronic disease.
- Post-vaccination finding in young animals.
- Lymphoid neoplasia.
LYMPHOPAENIA
Deficiency in circulating lymphocytes.
Occurs in infections- VIRUSES, SEPTICAEMIA.
Stress- Endogenous or exogenous corticosteroids.
-Transient altered distribution of lymphocytes between blood and lymphoid tissue.
NEOPLASIA OF THE HAEMATOPOIETIC SYSTEM
Haematopoietic neoplasia.
- Clonal proliferation of haematopoietic progenitor cells.
- Results from an accumulation of mutations.
- Sometimes specific agents are involved:
- RETROVIRUSES eg. FeLV, BLV, ALV
- HERPESVIRUSES eg. Marek’s disease, Burkitt’s lymphoma.
Tumour groups include- Leukaemia
- Plasma cell tumours
- Mast cell tumours
- Lymphoma
- Histiocytic disease
LYMPHOMA
A SOLID tumour of lymphoid cells.
Can mestastasise, entering blood and then bone marrow.
LYMPHOID LEUKAEMIA
Originates in bone marrow, then can pass to blood and tissues.
Cancer of the leukocytes; not a solid tumour.
LYMPHOMA VS LEUKAEMIA
Can sometimes be difficult to differentiate between the two.
CLASSIFICATION OF LEUKAEMIA
Can be classified by:
1. Degree of maturation of cells involved- acute or chronic. Mirrors clinical picture and progression of disease.
- Presence or absence of neoplastic cells in the blood- if NO neoplastic cells are being released in to the blood, we have a SUBLEUKAEMIC leukaemia (aleukaemic).
- Cell line involved- lymphoid or myeloid.
LYMPHOID LEUKAEMIA
B cell or T cell abnormalities/increases.
MYELOID LEUKAEMIA
From myeloid cell line:
- Erythroid
- Granulocytic
- Monocytic
- Megakaryocytic
- Mixed lineages can be seen.
CONSEQUENCES OF LEUKAMIA
- MYELOPHTHISIS- replacement of bone marrow population with neoplastic vells.
- EMH- Extramedullary haematopoiesis.
- SPLENOMEGALY/HEPATOMEGALY
- HAEMODYNAMICS- if WBC count is very high, the blood is thicker, impairing blood flow through microvasculature.
ACUTE LEUKAEMIA
- ACUTE UNDIFFERENTIATED LEUKAEMIA
- ACUTE LYMPHOBLASTIC LEUKAEMIA
- ACUTE MYELOID LEUKAEMIA
Can be seen at any age, but particularly seen in young animals.
Aggressive disease, present acutely; animal can be very sick.
Immature blast cells seen in circulation.
Most are thrombocytopaenic and anaemic, sometimes see pancytopaenia.
CLINICAL SIGNS OF ACUTE LEUKAEMIA
- Lethargy, anorexia, weight loss
- Pyrexia, shifting limb lameness
- Bleeding from mouth/nose, melaena (black, tarry faeces indicating GI haemorrhage)
- Splenomegaly, hepatomegaly (cause pale mucous membranes)
- Mild generalised lymphadenopathy
- Petechiae, echymoses.
CHRONIC LEUKAEMIA
- CHRONIC LYMPHOCYTIC LEUKAEMIA
- CHRONIC GRANULOCYTIC LEUKAEMIA
- POLYCTHAEMIA VERA
- ESSENTIAL THROMBOCYTHAEMIA
- Seen in older animals.
- Slower onset, progresses slowly.
- Can be asymptomatic.
- Neoplastic cells are well differentiated- they are mature in the circulation.
- Mild non regenerative anaemia may be seen, but generally other cell lines (RBCs) are unaffected.
CLINICAL SIGNS OF CHRONIC LEUKAEMIA
May be none; the leukaemia could be an incidental finding on routine screening.
- Gradual weight loss
- Lethargy
- Mild splenomegaly/hepatomegaly.
OTHER NEOPLASTIC CELLS IN THE CIRCULATION
Malignant histiocytes
Mast cells
etc. (see page 7, last slide)
