Cytology - FNA and skin scrape

Question 1

Cytology is

Answer 1

*The study of cells, their origin, structure, function, and pathology
*Using cells to identify abnormalities or malignancies
*We observe cells in small groups and in random distribution with no connection of how they interact with other cells

Question 2

In what species can you perform a cytology and why

Answer 2

*Is a diagnostic procedure
*Can be used in all species
*We collect cells from a body fluid, mucosal surface, secretion, or tissue
*Examine the cells microscopically
*Primarily done to differentiate inflammation from neoplasia
*Also used to investigate skin disease (dermatopathy)

Question 3

What can a cytology tell you

Answer 3

Properly collected, stored, and processed samples can give a rapid diagnosis and accurate treatment plan
◦ Identify benign or malignant masses
◦ Identify lesions (bacterial, fungal, parasitic)
◦ The type of fluid in a body cavity

Question 4

Advantages of cytology

Answer 4

*No extra or specialized equipment is required
*Very quick procedure
*Relatively non-invasive
◦ Animal usually awake
*Relatively low cost
*Quick results
◦ Same day or within a week

Question 5

Disadvantages of cytology

Answer 5

*Some training is required to identify the cells present
◦can be done by DVM or RVT
*May not be able to identify cells
◦ Can be sent in for a pathologist to identify
◦ Adds to the cost and time
*May need to supplement with histopathology

Question 6

Histopathology is

Answer 6

The study of cellular architecture (cells in relation to their neighbouring cells) and function
Requires tissue biopsies or lumps
◦Anesthesia often required
◦A piece is surgically removed and fixed in solution

Question 7

Advantages of histopahtology

Answer 7

Slide examined by trained pathologist
Can give more precise diagnosis

Question 8

Disadvantages of histopathology

Answer 8

Procedure is more involved and requires specialized equipment
More costly
Results may take several weeks
If a poor sample taken or poor collection method it can lead to misdiagnosis

Question 9

When to use a swab for cytology

Answer 9

*Performed when imprints, scrapings, or aspirates cannot be done
*Involves using a moistened (with sterile saline) sterile swab for dry lesions or a sterile swab for moist lesions
*Key to remember not to rub the swab across the lesion or slide but to gently roll across the to collect and transfer cells
*Ear swabs require gentle heat fixing - no others should

Question 10

Scrapings should be done for cytology when

Answer 10

*Generally used for firm lesions otherwise we can end up with too many cells on our smear
*Disadvantage is that the scraping is often superficial and only indicates secondary bacterial infection
*This procedure is typically used for diagnosis of Demodex

Question 11

Procedure with skin scrapings

Answer 11

1. Isolate the lesion (mass) with your off hand
2. Blot the surface of the lesion or mass
3. Hold a scalpel blade in your dominant hand at 90° or perpendicular to the lesion
4. Pull the blade across the lesion several times to remove a layer of cells
5. Take the collected material and spread it on a clean microscope slide (lots of methods depending on sample)
6. Can use oil to help sample adhere to slide
   ◦ can no longer stain
   ◦ especially when looking for parasites

Question 12

Imprints/impression smears are used for

Answer 12

*Performed on external lesions or from tissues removed during surgery or necropsy
*Contain fewer cells than scrapings and have a higher amount of contamination than aspirates
◦ Superficial lesions often only reflect a secondary infection or inflammation-induced tissue dysplasia

Question 13

How to perform imprints/impression smears

Answer 13

*Has modifications depending on the type of lesion
*The slide is gently touched to the lesion several times on several slides
*For tissues removed surgically the sample is blotted with gauze to remove excess fluid or blood
*Then the sample is gently touched to a clean slide in several spots
*Avoid excessive pressure

Question 14

What to do if there is a delay in taking the sample and making the impression smear

Answer 14

*When there is a delay between sample collection and making imprints cut a new surface with a scalpel blade

Question 15

Fine needle biopsy is used for

Answer 15

Used for masses, lymph nodes, nodular lesions, and internal organs

Question 16

Advantages of FNB

Answer 16

avoids superficial contamination

Question 17

Disadvantages of fine needle biopsy

Answer 17

fewer cells are collected compared to other collection methods

Question 18

Do you need so surgical scrub for a FNB

Answer 18

*For microbiological tests or for body cavity samples a surgical scrub is performed
*For other samples prepare by swabbing the area with alcohol
*Use a 21-25 gauge needle

Question 19

Fine needle aspirate is done with what and when

Answer 19

Use a 21 – 25 gauge needle and a 3 – 20 ml syringe
◦ The softer the tissue being aspirated the smaller the gauge needle and syringe should be used

Question 20

How to perform a FNA

Answer 20

1. Prep skin over mass with surgical scrub or alcohol
2. Secure the mass with your “off” hand and hold the syringe and needle in your dominant hand
3. Insert the needle into the mass and pull back on the plunger to create negative pressure
4. Redirect the needle several times within the mass while maintaining negative pressure
   * If suspicious of a mast cell tumour must inject diphenhydramine prior to poking
5. Release negative pressure and remove needle from mass
6. Remove syringe from needle and fill syringe with 2-3 mls of air
7. Reattach the needle
8. Gently force the sample from the needle onto a clean slide (or slides if sufficient sample)
9. Use the compression preparation, combination technique, or starfish smear to prepare sample

Question 21

Non-aspirate fine needle biopsy is used when and with what

Answer 21

*Also known as the capillary technique or stab technique
*Generally used for soft tissue masses, suspected lipomas or lymphomas, or lymph nodes
*Use a 22 gauge needle
◦ You may have it attached to a syringe just for ease of handling

Question 22

How to perform a non aspirate fine needle biopsy

Answer 22

1. Secure the mass with your “off” hand and hold the needle in your dominant hand
2. Direct the needle 5-6 times along the same path into the mass
3. Withdraw the needle and attach to a 10 ml air filled syringe
4. Expel the sample onto slides
   *Use the compression preparation,
   combination technique, or starfish smear to prepare sample
   *The needle may then be reinserted in another area of the mass and the process repeated to attain enough material to prepare more than one smear

Question 23

Tissue biopsy is and used for

Answer 23

*This is collecting a piece of tissue for either cytology, histology, or both
*Tissues or organs may be biopsied and include various methods such as the wedge biopsy or punch biopsy
*Can be done with the aid of ultrasound or endoscopy
*Skin biopsies should not be scrubbed or cleansed and any crusts, scales or surface debris should not be disturbed

Question 24

Wedge biopsy is used for

Answer 24

*Generally use a scalpel to collect
*Always include a transition zone
◦ Normal tissue to transition to abnormal tissue

Question 25

Advantage of a wedge biopsy

Answer 25

variable size specimen or the entire lesion

Question 26

Punch biopsy is what size and does it need sutures

Answer 26

Most commonly uses a 3, 4, 6, or 8 mm cutaneous biopsy punch
◦ 3 and 4 mm punches do not require suturing while 6 or 8 mm only require one to two sutures

Question 27

How to do a punch biopsy

Answer 27

*Generally collect 3-4 biopsies of various lesions
*Use local anesthetic
*Gently press and rotate the punch in one direction until the lesion has been completely encircled
Using fine forceps grasp tissue on its margins and place in 10% neutral phosphate-buffered formalin at a 1:10 ratio of tissue to fixative

Question 28

Centesis is

Answer 28

*The introduction of a needle into a body cavity or organ to remove fluid
*Abdominocentesis, thoracocentesis, arthrocentesis, and cystocentesis are the most common
*When collecting cerebral spinal fluid, synovial fluid, or fluids from the eye general anesthesia is required

Question 29

How to perform a centesis

Answer 29

*The area requires a surgical scrub or alcohol prep before beginning
*Must follow strict aseptic technique to prevent a secondary infection
*A 21 gauge needle is most commonly used to prevent cellular damage of the sample and attached to a 20 – 60 ml syringe
* Butterfly catheter may also be used
*Record the total volume of fluid collected

Question 30

Thoracocentesis can be done by

Answer 30

• Can use ultrasound guidance
• Needle inserted in the 7th or 8th intercostal space
• Always use a 3-way stopcock
• Patient can be standing or in lateral or sternal recumbency

Question 31

How to do an abdominocentesis

Answer 31

• Needle is introduced into ventral abdomen approximately 1 to 2 cm caudal to the umbilicus
• Place either left or right of the midline depending on placement of patient
• Patient can be lateral or standing

Question 32

Transtracheal/bronchial wash is

Answer 32

*These cells are collected from the trachea, bronchi, or bronchioles and assist with diagnosis of pulmonary disease

Question 33

How to do a transtracheal/bronchial wash

Answer 33

*Saline is infused at a rate of 0.5 – 1.0 ml/kg of body weight through a catheter into the trachea, bronchi, or bronchioles
*When the patient coughs the plunger of the syringe is pulled back several times to collect the sample
*A small amount of saline that is infused is actually collected
*Low mucus samples should be centrifuged to concentrate the cells before making smears

Question 34

What are the 3 ways to collect a transtracheal/bronchial wash

Answer 34

Orotracheal
Transtracheal
Nasotracheal

Question 35

How to do a orotracheal approach for a bronchial wash

Answer 35

Catheter is placed through an endotracheal tube
◦ Patient is anesthetized
◦ Preferred in small and fractious patients
◦ Patients do not cough with this technique so sample is withdrawn after a few seconds of insertion

Question 36

How to perform a bronchial wash through the nasotracheal approach

Answer 36

Catheter is placed through the nasal passage
◦ Patient is sedated

Question 37

How to do the transtracheal approach for a bronchial wash

Answer 37

Percutaneous approach(transtracheal): a catheter is placed through the skin and trachea
◦ Patient is sedated
◦ Less contamination from the pharynx and nasal cavity
◦ Uses an 18-20 gauge through the needle jugular catheter
◦ Requires a presurgical scrub and maintaining aseptic technique

Question 38

How to handle cytology samples

Answer 38

*Culture first when required
*Place on slide as soon as possible
◦ if fluid, may need to spin down
*Always make at least 2 slides or more
*Stain/fix as needed
◦ Always leave at least one slide unstained
*Try to use more than one technique for making smears to maximize diagnostic potential

Question 40

How to do a compression smear

Answer 40

aka “Squish” technique
•Expel the aspirate sample onto the middle of the slide (sample slide)
•Gently place a second slide (spreader slide) over the sample at a right angle to the sample slide
•Quickly and smoothly slide across the sample slide
•Do not put downward pressure on the sample slide
•Most common error is to rupture cells
•Modification is to rotate the spreader slide 45 degrees, and then lift it upward

Question 41

How to do a combination smear

Answer 41

Place the sample in the middle of your slide
•Take a spreader slide and hold it at a 45 ̊ angle to the sample slide
•Pull the spreader slide back until it makes contact with about 1/3 of the sample
•Slide the spreader slide forward in a smooth and rapid motion
◦Like making a blood smear
◦No downward pressure
Next the spreader slide is placed horizontally over the back third of the aspirate at a right angle to the sample slide (as done with compression smear)
Then spread the other direction

Question 42

What should a combination smear look like

Answer 42

Compression smear on back third
◦Untouched in the middle third
◦Front third is gently spread

Question 43

How to do a starfish smear

Answer 43

Place sample on the sample slide
•Using the point of a sterile needle pull the sample in several directions away from the pool of sample
•Best used for fragile samples or viscous samples
◦example – synovial fluid

Question 44

Samples from fluid processing

Answer 44

Prepare immediately after fluid collection
•EDTA tube should be filled first and smears made
•Smears can be a compression smear, blood smear, or a line smear

Question 45

How to do a line smear

Answer 45

•Best used for samples with low cellularity as it concentrates the cells
•Place a drop of fluid on the slide near the frosted edge
•Take a spreader slide and hold it at a 30 to 45 ̊ angle to the sample slide
•Pull the spreader slide back until it makes contact with the middle of the sample
•Slide the spreader slide forward in a smooth and rapid motion
•As you get ¾ through spreading the smear lift the slide directly up

Question 46

What are you trying to obtain with a smear

Answer 46

Proper preparation techniques
*Adequate sample material/cells
*PROPER LABELS
*A diagnostic sample!
*Most common stain done in clinic is Diff Quik. Some Vets will look in clinic, other will send to pathologist that prefer unstained samples

Question 47

What do proper slide labels have

Answer 47

Be sure your requisition form is filled out correctly
Slides need to be labelled WITH PENCIL and include
•Patient ID (pet’s name and owner’s last name)
•Site the sample was obtained from
•Date