Cytological examination

Question 1

Obtaining optimal information from a suitable sample requires…

Answer 1

Correct specimen collection or handling

Examination by an experienced Clinical Pathologist

Question 2

What causes false negatives of a cytological sample?

Answer 2

• Poor exfoliation of a neoplasm
• Failure to sample tumour tissue
• Extensive necrosis/inflammation present
• (also, a neoplasm may not be well-differentiated enough to allow an accurate diagnosis)

Question 3

What causes false positives of a cytological sample?

Answer 3

• Dysplasia (which can mimic neoplasia) may occur in inflammatory diseases

Question 4

What is FNCS?

Answer 4

FNA no suction

Question 5

What tubes do you put washes/lavages into?

Answer 5

Split samples into EDTA & sterile tubes & Process as soon as possible

Question 6

What are the 4 basic tests you carry out on fluids?

Answer 6

• Appearance of fluid
• Total protein content
• Nucleated Cell count (TNCC)
• Cell type/s content (sediment smear under microscope)

Question 7

How much fluid should you get from an Abdominocentesis/thoracocentesis? How can this show excess body cavity fluid?

Answer 7

A small amount of fluid is normal; too little for collection except in horses.
Marked hypoproteinemia is a common pathological cause of excess body cavity fluid

Question 8

How do you prepare aspirates?

Answer 8

If the fluid is turbid, make direct smears
If clear, centrifuge and smear the deposit
• An ordinary centrifuge may be used at a slow speed for a short period
• Special centrifuges (cytocentrifuges) yield better smears when cell count is low (e.g., CSF)
Air-dry rapidly & stain

Question 9

How do you prepare a core/tru-cut biopsy?

Answer 9

Roll Core along slide (gently) for cytology and then place in formalin pot for histology (Keep cytology preparations away from formalin fumes)

Question 10

What must you do to slides before viewing or packaging them?

Answer 10

Dry them

Question 11

What is a Transudate?

Answer 11

Excessive diffusion of plasma water from vasculature (transudation)

Question 12

What causes increased transudation?

Answer 12

– Altered hydraulic pressure E.g. increased alveolar capillary pressure: Caused by Na and water retention or portal hypertension
– Decreased plasma oncotic pressure e.g., hypoalbuminaemia

Question 13

What causes accumulation of transudate?

Answer 13

– impaired lymphatic drainage E.g, increased HP in posterior vena cava in venous congestion

Question 14

What causes protein poor transudate?

Answer 14

Healthy vasculature impermeable to proteins therefore, Transudates low in protein
“Protein poor” transudates
– Reduced plasma oncotic pressure – e.g., hypoalbuminaemia
– Once lymphatic drainage can no longer compensate
– Portal hypertension (pre-sinusoidal) e.g certain cirrhosis

Question 15

What causes protein rich transudate?

Answer 15

“Protein rich” transudates
– Proteins from interstitium (rather than vasculature)
– Varies by organ – 2g/dl in subcutis, 6g/dl in liver
– Portal hypertension (post-sinusoidal) e.g congestive cardiac failure
– May be referred to as “modified transudate”

Question 16

What is modified transudate?

Answer 16

• A transudate modified by the addition of protein or cells

* “Grey-zone” between transudate and exudate

Question 17

What is an Exudate?

Answer 17

• Exuding or oozing out of pores
• Inflammation → increased vascular permeability
• Plasma including protein leak from vasculature
• Hydraulic pressure to push protein rich fluid into interstitium; protein in interstitium promotes oncotic fluid draw
• Inflamed mesothelium more permeable

Question 18

What cells accompany exudate?

Answer 18

• Accompanied by inflammatory cells
– Neutrophils and macrophages
– Neutrophils, macrophages and lymphocytes
– Occasionally eosinophils or lymphocytes predominate
– Cell counts lower in FIP because vasculitis rather than pleuritis

Question 19

How do transudates look on cytology?

Answer 19

Appearance: Clear, watery
Protein poor: <20 g/l
Protein rich: 3-35 g/l
Nucleated cells <5 x109/l
Cell type/s: Few RBCs & Small mixed nucleated cell population
– neutrophils up to 60%
– lymphocytes, monocytes, macrophages, mesothelial cells

Question 20

How do exudates look on cytology?

Answer 20

Appearance: Turbid or Bloody/purulent
Protein: > 20 g/l
Nucleated cells: >5 x109/l
Cell type/s: Many RBCs; nucleated cells are mostly neutrophils, they may be degenerate (karyolysis), and bacteria may be present
Occur in inflammation, infection & necrosis (including necrosis within tumours)

Question 21

How do neoplastic effusions look on cytology?

Answer 21

Appearance: May be bloody and/or turbid
Protein: often > 35 g/l
Nucleated cells often 5-25 x109/l
Cell type/s: RBCs; mixed nucleated cell population; Neoplastic cells may be seen
Tumour cells have an irritant or “foreign body” effect producing inflammation; there may also be tumour necrosis

Question 22

How do haemothorax/peritoneum fluids look on cytology?

Answer 22

Appearance: bloody (but does not clot )
PCV variable >0.03 l/l)
Protein:>20 g/l
Nucleated cells: variable (similar to blood >2-15x109/l)
Cell type/s: RBCs; no platelets, mixed nucleated and mesothelial cells; possibly haemosiderophages

Question 23

How does uroperitoneum look on cytology?

Answer 23

Appearance: serosanguinous (may be an odour of urine especially if heated)
Protein: 10-30 g/l
Nucleated cells: low at first progresses to 5-15 x109/l
Creatinine and Potassium > plasma if recent or ongoing
Cell type/s: Many RBCs; mixed nucleated cells (macrophages, neutrophils, mesothelial cells)

Question 24

How does chyle/chylous effusion look on cytology?

Answer 24

Protein:>20 g/l
Nucleated cells: 5-20 x109/l
Cell type/s: Cells vary with age of lesion (mostly mature lymphocytes at first)

Question 25

What can cause a chylous effusion?

Answer 25

Trauma/spontaneous rupture of the thoracic duct (idiopathic chylothorax) But also can be caused by: – Heart failure, cardiomyopathy, pericardial effusion – Neoplasia, – Lymphangectasia Obstruction of minor lymphatics by chronic inflammation etc Non-thoracic duct origin chylous thoracic fluid common in cats including cardiomyopathy, diaphragmatic hernia etc

Question 26

What is the protein and cellular composition of synovial fluid?

Answer 26

``` Total protein (g/L): • Dog: <25 • Cat: <25 • Horse: <20 • Cow: <20 Total Nucleated Cells (x109/L) • Dog: <3 • Cat: <3 • Horse: <0.5 • Cow: <1 Cells form rows, >90% Mononuclear cells (predominantly monocytes/macrophages, and some lymphocytes) ```

Question 27

How does synovial fluid look in the case of Degenerative joint disease?

Answer 27

* total protein, TNCC often normal | * cytology – normal (occasional dysplastic synoviocytes)

Question 28

How does synovial fluid look in the case of Inflammation - non-septic?

Answer 28

(commonly immune mediated in dogs & cats) • total protein and TNCC increased • neutrophils predominate

Question 29

How does synovial fluid look in the case of Inflammation - septic?

Answer 29

(common in horses & ruminants) | • as above; bacteria visible or on culture

Question 30

What are the normal cells in a bronchiolar lavage?

Answer 30

Ciliated columnar epithelial cells normally predominate; <10% leucocytes (up to 20% eosinophils in cats)

Question 31

What does acute inflammation cell population look like?

Answer 31

• >70% of nucleated cells are neutrophils. | – The rest may be mononuclear cells (monocytes, macrophages, lymphocytes, plasma cells).

Question 32

What does non-septic or sterile acute inflammation cell population look like?

Answer 32

• Non-septic or sterile inflammation: | – neutrophils predominate but are well-preserved (non-degenerate).

Question 33

What does septic acute inflammation cell population look like?

Answer 33

• Septic inflammation: | – Neutrophils are degenerate (karyolysed) and bacteria are often present.

Question 34

What does 'Eosinophilic' acute inflammation cell population look like?

Answer 34

The cell content may be mixed, but 50% or more may be eosinophils.

Question 35

What is karyolysis?

Answer 35

Nuclear fading --> Anuclear necrotic cell

Question 36

What is pyknosis?

Answer 36

Nuclear shrinking --> Anuclear necrotic cell

Question 37

What is karyorrhexis?

Answer 37

Nuclear fragmentation --> Anuclear necrotic cell

Question 38

What does Epithelial neoplasia look like?

Answer 38

High yield, cells associated with one another, rafts, sheets, acini, cuboidal, columnar

Question 39

What does Spindle/Mesenchymal neoplasia look like?

Answer 39

Low yield, spindle shaped cells, usually single but may be in association/sheets, may be “matrix”

Question 40

What does Round cell neoplasia look like?

Answer 40

High yield, discrete round cells, not adherent

Question 41

What does a benign tumour look like?

Answer 41

A single population of uniform, large cells with pale, mildly granular cytoplasm and round to oval nuclei.

Question 42

What does a lipoma look like?

Answer 42

Soft, smooth, slow-growing, non- nodular painless masses occurring particularly in dogs Aspirate smears are of low cellularity, with a few clumps of benign connective tissue cells & adipocyte

Question 43

What is Pleomorphism and what is it characteristic of?

Answer 43

Neoplasia | Pleomorphism within a cell type (not lymphoid) - Pleomorphism is wide variation in cell shape.

Question 44

What is the cell/ cytoplasmic ratio like in neoplastic cells?

Answer 44

High and/or variable nuclear to cytoplasmic ratio - In normal benign tissue, adjacent cells have a fairly constant, often low nucleus-to-cytoplasmic ratio. In malignant tissue it may be high, or it may vary hugely in adjacent cells, indicating unregulated, asynchronous growth

Question 45

Is Basophilia/ hyperchromasia associated with neoplasia?

Answer 45

Basophilia of the cytoplasm with Romanowsky stains is caused by high RNA content of immature cells There may be vacuolation, granularity or phagocytosis of other cells.

Question 46

What do carcinomas look like?

Answer 46

Cellularity is often high; rounded or cells with distinct cell boundaries forming clusters, sheets or sometimes acini.

Question 47

What do sarcomas look like?

Answer 47

Cellularity is often low; often single, elongated/spindle-shaped cells with indistinct cell boundaries. It is often difficult to identify a specific cell of origin Entwined nature of mesenchymal cells in tissues means they are difficult to persuade out of the mass with gentle aspiration

Question 48

What do round cell tumours look like?

Answer 48

``` Cellularity is usually high; rounded or oval cells with distinct borders occur singly or small clusters Examples include • Lymphoma • Plasmacytoma • Melanoma • Mast cell tumor • Histiocytoma • Transmissible venereal tumour (TVT) ```