Introduction to cytology

Question 1

What are the indications for using cytology?

Answer 1

• Characterise a detected abnormality e.g. mass, infiltrative lesion, organomegaly, ulcerative lesion, joint effusions
• Staging of cancer
• Diagnostic work-up of patients with fever of unknown origin, hypercalcemia, monoclonal gammopathy
• Bone marrow aspiration for investigation of non-regenerative anemia, thrombocytopenia, bicytopenia or pancytopenia

Question 2

Define histology

Answer 2

The study of disease through the evaluation of tissue sections

Question 3

Define cytology

Answer 3

The study of disease through the evaluation of cells

Question 4

What are the pros and cons of cytology?

Answer 4

• Less invasive
• Less than 24hrs for results
• Low cost
• Can be assessed in house
• Excellent cellular assessment
• Can assess fluids
• Immunostains limited
• Can see tissue architecture

Question 5

What are the pros and cons of histology?

Answer 5

• More invasive
• 2-5 days for results
• Higher cost
• Cant be assessed in house
• No assessment of fluids
• Can use immunostains
• Can see tissue architecture

Question 6

What are the limitations of cytology?

Answer 6

• Sometimes difficult to achieve a final diagnosis on a cytology sample even for an experienced clinical pathologist as tissue architecture cannot be assessed
• May be non-representative or inadequate quality
• We can look at slides straight away in clinic but we often need to send the sample to an external laboratory

Question 7

What can cytology be used for?

Answer 7

• Fluid analysis
• Bone marrow
• Round cell tumours
• Detect inflammation
• Detect neoplasia
• Differentiate between benign and malignant lesions and identify tumour type in many cases

Question 8

What is the source of cells in tissues?

Answer 8

Palpable lesions (masses), internal organs, lymph nodes, BM

Question 9

What is the source of cells in fluids?

Answer 9

• Body fluids: Abdominal/thoracic effusions, joint fluid, cerebrospinal fluid
• Lavage and wash fluids (airways and urinary tract)

Question 10

By which methods can cells be collected?

Answer 10

• Fine needle biopsy: capillary sampling/aspiration
• Touch imprints or scrapes
• Swabs
• Aspiration of bodily fluids
• Administration and collection of body fluids

Question 11

Compare Fine needle biopsy: capillary sampling vs aspiration

Answer 11

We can use aspiration (FNA) or non-aspiration technique (FNCS) (always try the non-aspiration technique first especially for vascular organs and lymph nodes)

Question 12

What are touch imprints/scrapes used for?

Answer 12

Ulcerated skin lesions, surgical or ultrasound guided biopsy

Question 13

How can cellular yield be increased when sampling?

Answer 13

• Take several aspirates and make multiple smears
• Stain one to determine if cellular/representative
• Submit all the slides!

Question 14

How can diagnostic quality of a sample be increased?

Answer 14

• Apply a light touch to prevent cells from being smashed

- To thin? To thick? Consider the appropriate preparation technique

Question 15

How can haemodilution be reduced?

Answer 15

• Be quick and use non-aspiration technique first
• Don’t want a lot of blood to contaminate
• Fine needle capillary sampling will reduce haemodilution

Question 16

How should slides be prepared based on the sample type?

Answer 16

• Masses and organs: squash preparation
• Biopsies: imprint
• Fluids: smear (direct +/- sediment depending on cellularity) + aliquot in plain and EDTA to be sent to clinical pathology laboratory

Question 17

What is a ‘line prep’ used for?

Answer 17

Good for fluids suspected to be poorly cellular

Question 18

How are cytology slides processed?

Answer 18

Cytology slides can be stained with quick stains for evaluation in-house

• Checking quality/cellularity of the sample (so you can repeat if needed) and preliminary evaluation (e.g. distinguish inflammation from neoplasia)
• For surgical emergencies (e.g. septic effusions)
• Do not stain all the slides as you may need to send them to a clinical pathology laboratory for expert opinion

Question 19

How should slides be processed to send to an external lab?

Answer 19

• Even if you have stained one (or more), include all the slides in the submission
• Make sure slides are labelled with patient ID and site and in pencil (or it will be washed out during staining)
• Use rigid plastic mailers
• Do not ship together with formalin pots

Question 20

Describe the approach to analysing the cytology slide

Answer 20

Be consistent:
- Always use the same order
- Do not jump immediately to a conclusion
Be thorough: Scan the entire slide and all the stained slides
Do not jump immediately to high power

Question 21

What is the first step in analysing a cytology slide?

Answer 21

x1 magnification
with the naked eye
- Slide labelling: patient and site?
- Staining and distribution of the material

Question 22

What can be assessed on Low power (4x-10x lens)?

Answer 22

Look for the monolayer

• Quick scan for quality, cell preservation and distribution (choose the ‘sweet spot’)
• Scan for big stuff (larvae, fungi, eggs, foreign material)
• Preliminary identification of cell types and their arrangement
• Assess background

Question 23

What should you be aware of when analysing a cytology slide?

Answer 23

Artefacts

• Ruptured cells (too much pressure!)
• Poorly stained (too thick or too quick!)

Question 24

What can be assessed on High power (40x, 50x)

Answer 24

More accurate identification of cell types

• Inflammatory, tissue cells, or a mix?
• Classify inflammation- the type may help determine the aetiology: Neutrophilic, eosinophilic, lymphocytic, histiocytic, mixed
• Identify tissue cells: Normal or abnormal tissue

Question 25

Neutrophilic inflammation is called?

Answer 25

Suppurative

Question 26

What can be assessed on Very high power (100x)?

Answer 26

• Further characterisation of nuclear and cytoplasmic detail

- Better identification of microorganisms