Cytology in practice Flashcards
Why do cytology?
quick, easy, cheap, non-invasive, low risk, screening tool, can establish a diagnosis or disease process
Limitations - cytology
relies on sample quality (collector skill, smear, tissu eexfoliation, site of collection), interpreter of smears, no information about tissue architecture (vs histopathology), diagnostic challenges
Histopathology - advantages
more expensive (sterile), slow (48 hr), poor detail for round cell tumours
Histopathology - disadvantages
tissue architecture, tumour grading, immunohistochemistry more available.
What samples can you take for cytology?
ASPIRATION OR IMPRINTS: superficial masses, LN, organs and deep masses
FLUIDS: body cavity, joints, respiratory space, CSF
When to do fine needle biopsy?
solid or fluid filled masses, visual or US guidance, no negative pressure applied to syringe, small guage needle (22-24), insert into mass several times, masses with necrotic centre you must sample the wall not just the centre then use air filled syringe to expel cells onto slide.
Distinguish FNA and FNP
FNA = fine needle aspirate. negative pressure applied to syringe. use only if FNB not possible.
FNB = fine needle biopsy, NO negative pressure applied to syringe. first choice method.
What makes a smear of a good quality? 3
cells nicely spread out, not ruptured, not just chromatin fibres from nuclei visible.
3 goals of smear preparation
thin areas with good cell spread, minimise cell damage, minimise blood content
Another name for a touch impression?
Imprint
What are imprints good for?
Evaluation of excised tissue or superficial lesions. Made before the tissue is placed in 10% buffered formalin and submitted for histopathology
How to make an imprint
Use fresh cute surface of tissue, blot until dry, imprint directly onto glass slide, tissue should be roled agaunst the slide, 4-5 imprints per slide, allow to air dry and then stain.
How is fluid collected? 3
With EDTA - clot prevention
sterile pot - bacteriology
fresh - slide preparation (direct smear, line preparation, squash preparation, concentration techniques)
What is the most important thing to determine from a cytology smear?
Inflammatory or neoplastic
What to determine if lesion is inflammatory
Septic or non-septic
What to determine if lesion is neoplastic
Round cell, epithelial or spindle cell
Indicators of sample quality - 5
- enough cells to examine
- preservation of cells
- adequate spreading
- representative of the lesion?
- do we expect normal cells/what are normal cells from this area?
How to tell if sample is inflammatory?
Dominated by inflammatory cells - neutrophils, eosinophils, lymphocytes, macrophages
How to tell if sample is neoplastic?
Sample dominated by tissue cells
What if the sample is BOTH inflammatory AND neoplastic?
Need experience/2nd opinion to tell if:
- inflammation with secondary dysplasia OR
- neoplasia with secondary inflammation
Indicators of septic inflammation
contains bacteria/organisms, degenerate/lytic neutrophils, bacteria must be intracellular, if extracellular may be contaminants
Indicators of non-septic inflammation
no bacteria or organisms seen, neutrophils are non-degenerate, lack of identifiable bacteria and presence of non-degenerate neutrophils
Outline degenerative changes in neutrophils 4
- nuclear change
- nucleus swells, loses lobulation and becomes paler (chromatin less condensed)
- secondary to release of bacterial toxins
- if present, consider septic inflammation even if bacteria not seen.
What does an increased number of macrophages suggest? What if neutrophils are present too?
- Inflammatory lesion - a granulomatous inflammation (e.g. mycobacterium spp).
- If neutrophils too - pyogranulomatous inflammation (fungal infections).
