Cytology and sampling techniques

Question 1

Define cytology

Answer 1

the study of cells

Question 2

What is another word for cytology?

Answer 2

cytopathology

Question 3

Describe cytology

Answer 3

branch of pathology that studies and diagnoses diseases at the cellular level

Question 4

List the pros of cytopathology

Answer 4

not highly invasive
usually no need for local anaesthesia or sedation
aspiration of individual/grouped cells, loss of tissue architecture
less sample processing required
faster result turnaround
cheaper

Question 5

List the cons of cytology

Answer 5

not as accurate as histopathology on some occasions

Question 6

List the pros of histopathology

Answer 6

usually gold standard for diagnosis:
can see architecture of tissue
more accurate

Question 7

List the cons of histopathology

Answer 7

more invasive sampling
usually requires local anaesthesia and potentially sedation or general
aspiration of tissues, preservation of tissue architecture
prolonged sample processing required
slower result turnaround
more expensive

Question 8

Which technique is more suitable for seeing cell organisation?

Answer 8

histopathology

Question 9

List the steps of cytological diagnosis

Answer 9

1. sample collection
2. smear preparation and staining
3. examination under the microscope

Question 10

What does proper sampling ensure?

Answer 10

adequate representation of material to be examined and good morphological preservation of cells

Question 11

What is FNA ideal for?

Answer 11

cutaneous or subcutaneous masses

Question 12

When is the non-aspiration method used?

Answer 12

without applying suction with a syringe

useful in highly exfoliating lesions, highly vascular lesions, or where cells are fragile

Question 13

When is the aspiration method used?

Answer 13

suction with a syringe attached to the needle

needed in poorly exfoliating masses in order to increase the cell yield

Question 14

When are impression smears used?

Answer 14

useful in exudative skin lesions and preparation of cytology smears from biopsy (tissue) specimens
impression smears may yield only surface contamination and may not be representative of the lesion

Question 15

When are tissue scrapings used?

Answer 15

indicated in flat lesions that cannot easily be aspirated or on biopsy specimens that are poorly exfoliating

Question 16

What can swabs be used for?

Answer 16

ears, vaginal smears, fistulous tracts

Question 17

Describe the aspiration method

Answer 17

The mass is stabilised with one hand, while the needle attached to a syringe is introduced into the centre of the mass
Negative pressure is applied using the syringe in order to increase the cell yield
The needle is re-directed several times in different areas of the mass while the negative pressure is maintained – alternatively, multiple samples can be taken from the same mass by aspirating several areas separately
The needle is removed from the syringe and air is drawn into the syringe. The needle is replaced onto the syringe and some of the tissue in the barrel and hub of the needle is expelled onto one end of a glass microscope slid

Question 18

What can cause a haemodiluted sample when aspirating?

Answer 18

negative pressure causing blood contamination

Question 19

Describe the non-aspiration method

Answer 19

○ Technique is similar to standard aspiration technique, except no negative pressure is applies during collection
Barrel of syringe is filled with air to the collection attempt to allow rapid expulsion of material onto a glass slide
The needle is rapidly moved back and forth in a stabbing motion in an attempt to stay along the same tract
The needle is then withdrawn and the material in the needle is rapidly expelled onto a clean glass slide

Question 20

What is a benefit of the non-aspiration method?

Answer 20

less blood contamination

Question 21

List and describe 2 sampling errors of FNA

Answer 21

1. geographical miss: aspirate areas adjacent to the lesion, not the mass
2. aspirate from the necrotic centre/adjacent area on inflammation of a tumour

Question 22

How do you transfer the cells collected on a swab onto a slide?

Answer 22

by rolling

Question 23

Describe how to make a cytology smear from excised tissue

Answer 23

The tissue is trimmed so that a fresh surface is created for making other impression smear
The surface of tissue is blotted several times against an absorbent material to remove excess blood and tissue fluid
The tissue is gently pressed (not smeared) several times against the surface of a clean glass slide

Question 24

Describe the squash preparation method

Answer 24

a portion of the aspirate is expelled onto a glass microscope slide, and another slide is placed over the sample to spread it. Gentle digital pressure can be applies to the top slide to increase spread - care must be taken not to place excessive pressure on the slide, causing the cells to rupture
The slides are smoothly slid apart. This usually produces well-spread smears but may result in excessive cell rupture

Question 25

Describe the needle spread / starfish method

Answer 25

A portion of the aspirate is expelled onto a glass microscope slide
The tip of a needle is places in the aspirate and moved peripherally, pulling a trail of the sample with it
This procedure is repeated in several directions, resulting in a preparation with multiple projections

Question 26

Give 2 examples of issues with smears

Answer 26

• excessive cell disruption during smear preparation due to excess pressure
• inadequate cell spreading during preparation so get droplets of cells, no monolayer and hard to visualise

Question 27

List 3 examples of Romanowsky-type stains

Answer 27

1. Wright stain
2. Giema stain
3. Diff-Quik stain

Question 28

What must first be done to slides prior to staining and why?

Answer 28

must air dry them

helps cell fixation and adhesion to slide

Question 29

Give an example of a Romanowsky-type stain that is aqueous-based

Answer 29

Diff-Quik

Question 30

Give an example of Romanowsky-type stains that are methanol-based

Answer 30

Wright

Giemsa

Question 31

What may aqueous-based stains fail to stain?

Answer 31

the granules of mast cells, basophils and large granular lymphocytes which can cause difficulty in cell identification and classification

Question 32

List the orders of the colours of dye in a Diff-Quik stain

Answer 32

1. fixative
2. red dye
3. blue dye

Question 33

List the fluids that can undergo cytological examination

Answer 33

abdominal fluid
thoracic fluid
joint fluid
cerebrospinal fluid
respiratory wash
prostatic wash
urine

Question 34

Explain why a fluid may appear cloudy / purulent

Answer 34

more WBCs producing an exudate

Question 35

Explain why a fluid may appear red

Answer 35

erythrocytes

Question 36

Explain why a fluid may appear milky

Answer 36

chyle: lots of bile

Question 37

Describe the process of sedimentation of fluids

Answer 37

sample collection
centrifugation
use cell pellet to make stained sediment smear

Question 38

What is the benefit of cytocentrifugation?

Answer 38

cells concentrate onto one area of the slide so don’t have to be looked for

Question 39

List the important features of sending glass slides to the lab

Answer 39

Label smears clearly
Prefer glass slides with frosted edges
Use a pencil to write on the frosted edge to avoid erasing during fixation and staining
If you send multiple slides from the same location, label the slides accordingly e.g “Spleen 1/5,” “Spleen 2/5”, etc

Question 40

What should be written on a glass slide being sent to the lab?

Answer 40

patient’s name
owner’s name
location of lesion
date

Question 41

What is important when transporting glass slides to the lab?

Answer 41

use appropriate air-tight, rigid container to avoid breaking slides and avoid exposure to formalin fumes which can make slides uninterpretable