Introduction to cytology Flashcards
What are the indications for using cytology?
- 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
Define histology
The study of disease through the evaluation of tissue sections
Define cytology
The study of disease through the evaluation of cells
What are the pros and cons of cytology?
- 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
What are the pros and cons of histology?
- 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
What are the limitations of cytology?
- 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
What can cytology be used for?
- Fluid analysis
- Bone marrow
- Round cell tumours
- Detect inflammation
- Detect neoplasia
- Differentiate between benign and malignant lesions and identify tumour type in many cases
What is the source of cells in tissues?
Palpable lesions (masses), internal organs, lymph nodes, BM
What is the source of cells in fluids?
- Body fluids: Abdominal/thoracic effusions, joint fluid, cerebrospinal fluid
- Lavage and wash fluids (airways and urinary tract)
By which methods can cells be collected?
- Fine needle biopsy: capillary sampling/aspiration
- Touch imprints or scrapes
- Swabs
- Aspiration of bodily fluids
- Administration and collection of body fluids
Compare Fine needle biopsy: capillary sampling vs aspiration
We can use aspiration (FNA) or non-aspiration technique (FNCS) (always try the non-aspiration technique first especially for vascular organs and lymph nodes)
What are touch imprints/scrapes used for?
Ulcerated skin lesions, surgical or ultrasound guided biopsy
How can cellular yield be increased when sampling?
- Take several aspirates and make multiple smears
- Stain one to determine if cellular/representative
- Submit all the slides!
How can diagnostic quality of a sample be increased?
- Apply a light touch to prevent cells from being smashed
- To thin? To thick? Consider the appropriate preparation technique
How can haemodilution be reduced?
- Be quick and use non-aspiration technique first
- Don’t want a lot of blood to contaminate
- Fine needle capillary sampling will reduce haemodilution
How should slides be prepared based on the sample type?
- 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
What is a ‘line prep’ used for?
Good for fluids suspected to be poorly cellular
How are cytology slides processed?
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
How should slides be processed to send to an external lab?
- 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
Describe the approach to analysing the cytology slide
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
What is the first step in analysing a cytology slide?
x1 magnification
with the naked eye
- Slide labelling: patient and site?
- Staining and distribution of the material
What can be assessed on Low power (4x-10x lens)?
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
What should you be aware of when analysing a cytology slide?
Artefacts
- Ruptured cells (too much pressure!)
- Poorly stained (too thick or too quick!)
What can be assessed on High power (40x, 50x)
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
Neutrophilic inflammation is called?
Suppurative
What can be assessed on Very high power (100x)?
- Further characterisation of nuclear and cytoplasmic detail
- Better identification of microorganisms
