Lecture 4 Flashcards
What is cytopathology?
The branch of pathology that studies and diagnoses disease at a cellular level
What are some of the advantages and disadvantages of cytopathology against histopathology?
- Cost is small (obtaining the samples and the techniques used)
- Anaesthesia is not needed to take this sample (generally)
- Equipment used to obtain samples is very minimal
- Complications due to obtaining the tissue is very rare
- Scarring from the procedure will be minimal if at all compared to always scarring from an operation or biopsy
- Quick procedure, results usually within 24-48hrs
- It is more possible for errors to occur in cytopathology
What are the 2 major branches of cytopathology?
- Aspiration cytopathology (involving the use of a needle to obtain cellular samples that can be analysed)
- Exfoliative cytopathology (cells that have been exfoliated and extracted from the body and body cavities) e.g gynaecological samples, body fluid cytopathology, GI tract cytopathology and scrape cytopathology
What is aspiration cytology and how is it used?
Using a fine needle to aspirate cellular material to make a diagnosis.
It can be used on any lesion in the body:
Palpable lesions - easily targeted by palpation (feel the presence of a lesion by touch)
Non-palpable lesion - Aided with imaging (CT scan, ultrasound, endoscopy)
Where is the most common place in the cervix that you would find a pathological change?
The squamocolumnar junction (SCJ) in the ectocervix because the ‘transformation zone’ is full of constantly changing cells which means that this leaves this area more prone to pathological change
What are 3 methods of sample collection for respiratory exfoliative cytopathology?
- Sputum sample
- Bronchial brush/ wash
- Bronchoalveolar lavage (BAL)
How is sputum analysed?
- Level of infection detected on the sputum colour chart
What is a bronchial brush/wash?
- A method of obtaining samples via a flexible fibre optic bronchoscope
- High accuracy rate for squamous cell, adeno and small cell carcinomas
What is a brochoalveolar lavage?
- Performed in the same way as the bronchial brush, however the region is actually irrigated to take the sample away
- Useful in the detection of opportunistic infections (Fungal pneumonia etc) and diffuse lesion cancers
What are some of the common samples taken to be used during body fluid cytopathology?
Pleural fluid
Pericardial fluid
Peritoneal fluid
Cerebrospinal fluid
What are the 2 methods of collecting samples of the GI tract?
- Endoscopic retrograde cholangiopancreatography (ERCP) combining endoscopy and fluoroscopic imaging (usually used in the bile and pancreatic ducts
- Brushings using the endoscope (usually used to treat oesophageal and gastric lesions)
How are cytopathological samples processed?
- Usually placed onto a slide as a smear and stained with a ‘quick stain’ (e.g diff quick)
- For fine needle aspiration (FNA) samples, centrifuge smears may be taken taking samples (cellular pellets) from the supernatant which means the sample material of interest is now more concentrated, this is then stained with H and E or Diff Quick
What are some of the cytopathology techniques that can be used?
- Simple histochemical stains
- Immunocytochemistry
- Flow cytometry (FACS)
- Electron microscopy
How are samples prepared for electron microscopy?
- Fixed is frozen sections can be used
- Fixed using gluteraldehyde (this produces best results)
- Instead of being embedded into paraffin wax, electron microscope samples are embedded in resin e.g epoxy resin to allow for the ultra thin sectioning that an ultramicrotome or cryoultramicrotome will have to do
Although mostly superseded by immunocytochemistry where is electron microscopy still helpful?
In the diagnosis of particular diseases:
- Metabolic and inherited disorders
- Peripheral nervous system disorders
- Myopathies (muscle disorders)
