Introduction to cytology

Question 1

Cytology

Answer 1

Evaluation of cells on a slide
Can be done in practice
Cell morphology is better preserved

Question 2

Histology

Answer 2

Evaluation of tissues on a slide
Performed in laboratories
Cell morphology is less easy to evaluate but you can see tissue architecture

Question 3

Advantages of cytology

Answer 3

Samples can be obtained and analysed very quickly - useful for rapid diagnosis

Samples can be obtained without sedation/minimal sedation

Inexpensive

Question 4

Disadvantages of cytology

Answer 4

Often can only give an indication of the type of lesion (inflammatory vs neoplastic) and a less good indication of the malignant potential

Definitive diagnosis can be hampered by concurrent inflammation

Some lesions do not exfoliate well so there is a small risk of tumour seeding or haemorrhage

Question 5

Methods for obtaining cytology samples

Answer 5

FNA
Impression/swab smear
Squash preparation
Scrapings
Fluid smear
Fluid cytospin preparation

Question 6

Needle only FNA

Answer 6

Useful for vascular lesions and lymph nodes

Reduced blood contamination and helps maintin integrity of fragile cells

Less useful for very solid/fibrous tumours

Question 7

Continuous suction FNA technique

Answer 7

Better for solid/fibrous masses

Continuous suction applied through syringe

Remember to release suction gently before removing needle

Can be associated with lots of blood contamination

Question 8

Intermittent suction FNA technique

Answer 8

Preferred for small masses where redirection not possible or internal masses with risk of leceration by redirecting

Withdraw and release the plunger several times

Needle inserted into mass and suction applied and released continuously, then suction released before the needle is withdrawn

Question 9

Cautions when aspirating lymph nodes

Answer 9

When aspirating lymph nodes or large masses, it is often preferable to avoid aspirating the centre bcause they can contain a necrotic centre.

In cases with generalised lymphadenopathy, sample a minimum of 2 lymph nodes.

Aspiration of the mandibular lymph nodes is not recommended since they can often be ‘reactive’ due to the presence of dental disease, which can confound the cytological interpretation.

Question 10

Cautions when aspirating vascular structures (e.g. liver and spleen)

Answer 10

Check platelet count (and coagulation times for liver)

If suspecting haemangiosarcoma, don’t aspirate

Question 11

Cautions when aspirating masses on the adrenal gland

Answer 11

May be phaeochromocytomas (tumours of the adrenal medulla which produces catecholamines like adrenaline).

Aspiration of phaeochromocytomas can lead to release of adrenaline, and consequentially tachycardia, arrhythmias and hypertension, therefore aspiration of adrenal masses should be performed with extreme care and may not be recommended in practice.

Question 12

Cautions for FNAs of masses from prostate or bladder

Answer 12

Don’t do it as there is a high risk of tumour seeding if they are carcinomas

Can instead to prostatic wash or catheter suction biopsy

Question 13

Cautions when FNAing thoracic masses

Answer 13

Can be problematic due to risk of accidental pneumothorax if the lung is penetrated

Masses within mediastinum or close to body wall are less risky - need ultrasound guidance

Question 14

Solutions used for Diff-quik staining

Answer 14

Methanol solution

Xanthine dye

Thiazine dye (make sure not to put in for too long)

Question 15

Stains to use for cytology

Answer 15

Diff-quik - most common, excellent nuclear and cytoplasmic staining, cheap and quick, does not always stain mast cell granules well

Giemsa - referral labs, stains mast cell granules well

Papanicoloau - gives better nuclear detail, may allow earlier detection of neoplastic cells

Toludine blue - may give better visualisation of mast cell granules

Periodic acid schiff - identification of fungal hyphae

Question 16

Neutrophilic inflammation

Answer 16

> 70% neutrophils

Most commonly occurs secondary to bacterial infection

Can occur with foreign body reactions, immune mediated diseases, or neoplasia

If high numbers seen then look for bacteria and degenerative changes in the neutrophils

Question 17

Degenerated neutrophils vs toxic neutrophils

Answer 17

Degenerated neutrophils are ONLY found in tissues and toxic neutrophils are ONLY found in the blood.

Question 18

Cause of neutrophil degeneration

Answer 18

Usually caused by the presence of bacteria - If you see degenerated neutrophils then you should be particularly careful to search for bacteria on the slide.

The presence of intracellular bacteria within the neutrophils is diagnostic for bacterial infection.

Question 19

Morphology of degenerated neutrophils

Answer 19

Poorly lobulated nucleus which looks irregular in shape and is less intensely stained

Question 20

How to tell contaminant bacteria from true infection on cytology

Answer 20

Contaminant bacteria may be more mixed populations of rods and cocci, and are frequently extracellular (rather than intracellular) and there would be a lack of an inflammatory response.

True infections are more likely to be a monomorphic population of bacteria, with intracellular organisms within neutrophils, +/- degenerative changes in neutrophils and an associated inflammatory response.

Question 21

Mixed inflammation

Answer 21

More chronic inflammatory lesions will contain more macrophages, lymphocytes and plasma cells.

High numbers of eosinophils can be seen in parasitic or hypersensitivity reactions.

Question 22

Identifying round cells on cytology

Answer 22

Individualised

Cytoplasmic borders are distinct

Often readily exfoliate/highly cellular

Round/oval shape to cell and nucleus

Question 23

Identifying epithelial cells on cytology

Answer 23

Clustered (tight)

Cytoplasmic borders often distinct

Variable exfoliation/cellularity

Round to polygonal shape of cell, round/oval nucleus

Question 24

Types of mesenchymal (spindle) cell

Answer 24

Individualised and clustered (loosely)

Cytoplasmic borders can be indistinct (whispy)

Often poor exfoliation/cellularity

Oval to fusiform shaped cell, oval to elongated nucleus

Question 25

Types of round cells

Answer 25

Mast cells - usually contain moderate amounts of cytoplasm and many purple cytoplasmic granules Plasma cells - contain moderate amounts of deep blue cytoplasm with a clear golgi zone and an eccentric nucleus Lymphocytes - contain scant cytoplasm Histiocytes - ontain moderate amounts of pale blue cytoplasm, eccentric nucleus, no granules. Can see binucleated cells.

Question 26

Criteria of malignancy

Answer 26

Pleomorphism - anisocytosis - anisokaryosis - macrocytosis - macrokaryosis Increased nuclear: cytoplasmic ratio Nucleolar changes - multiple, prominent nucleoli - macronucleoli - irregularly shaped nucleoli Multinucleation Bizarre mitotic figures

Question 27

What can you class as a malignant tumour from cytology

Answer 27

Contains cells that consistently have at least 3 criteria of malignancy

Question 28

'Skipocytes' (damaged cells)

Answer 28

Can be identified by the lack of a visible cytoplasmic border, and often the nucleus appears less intensely stained (pale pink). Nucleoli can also look quite prominent but this is an artefact due to the cell damage.

Question 29

Malignant tumour types that appear cytologically benign

Answer 29

The classic example of this would be anal sac adenocarcinoma, which has a ‘naked nuclei’ appearance to the cells. Cytological criteria of malignancy are mild, however the tumour is frequently metastatic. Other neuroendocrine tumours like thyroid tumours can also appear cytological benign despite being malignant neoplasms.

Question 30

Lymphoproliferative tumours/lymphoma

Answer 30

Normal lymph nodes should contain mostly (>90%) small lymphocytes (smaller than 1x neutrophil in diameter), with low numbers of intermediate (same size as neutrophil) and large sized lymphocytes (bigger than neutrophils). The presence of a mixed/pleomorphic population of lymphocytes is usually a sign of a benign reactive hyperplasia of the lymph node, whereas the presence of a monomorphic population of large lymphocytes is suggestive of a neoplastic population of lymphocytes (lymphoma).