Histopathology and Cytopathology

Question 1

Answer 1

• Histopathologists (interested in tissue structure): trying to stage disease
• Biopsies
• Resection specimens
• Frozen sections (real time)
• Post-mortems (hospital or Coroner’s)
• Cytopathologists (interested in cells):
  
  • Smears
  • Fine needle aspirates

Biopsies: (NIC)

1. Is it normal?
2. Is it inflamed? If so, what’s cause?
3. Is it cancer? If so, what type?

Resection specimens:

• How far has cancer spread?
• Is it all out?

Frozen section: 24 hours

• Rapid diagnosis; Is it cancer? Is it all out?
• How sections are obtained:
  
  • Specimen must be properly labelled
  • Fix in formalin – crosslinks proteins + slows decomposition
  • Embed in paraffin wax
  • Cut sections (very thin) and stain
• Use of sections:
  
  • Stain e.g. Haematoxylin + eosin (H&E), gram, ZN stain (for TB)
  • Use antibodies to identify specific antigens = immunohistochemistry
  • Carry out molecular tests e.g. oestrogen receptors in breast cancer

Time taken for histopathology result to reach clinician: (probably don’t need to know)

• Frozen section: 30 minutes
• For biopsies: 2-3 days
• For resection specimens: 5-7 days

Cytopathology:

• Looking at individual cells not tissues – pretty much real time, rapid
• Used for fine needle aspirations
• Used for cervical screening
• Most cytology done in real time, VERY quick
• Billy’s (slides) skin biopsy shows Kaposi’s sarcoma = HIV/AIDS-defining disease
• Immunocytochemistry for CD31 (CD31 marks vascular endothelium) to show vascular tumour infiltrating collagen bundles à endothelial cell tumour
• A fine needle aspiration of one of enlarged nodes revealed mixed cell population
• The diagnosis is of reactive lymphadenopathy