What is the gold standard in the diagnosis of cancer?
What % of the work of a histology lab is convered with the diagnosis and treatment of cancer?
Why is it important that cancer diagnoses are made correctly?
False positives and negatives are potentially disastarous and expensive
Why might false positive cancer results be disasterous?
A diagnosis of cancer can lead to radical treatment that is disfiguring or harmful
Why can false negative cancer results be potentially disastrous?
Because the patient will come back with more advanced tumours with a worse prognosis
Why are most cancers easily diagnosed histologically?
Because most cases show histological features that are at either end of the benign-malignant spectrum
What happens when cases are in the middle of the benign-malignant spectum histologically?
It produces problems of diagnosis, and therefore management
What are the categories of samples sent for cancer diagnosis?
What forms of tissue sample might be received for histological testing?
- Diagnostic biopsy
- Excisional specimen
What is the main purpose of diagnostic biopsies?
Give two examples of methods of obtaining diagnostic biopsies
- Needle core
What is the main purpose of obtaining excisional specimens
Done with curative intent
What tissues are amenable to histological evaluation?
What is evaluated in cytology?
Cells suspended in fluid
What are the ways of obtaining cytology samples?
How can cells be exfoliated?
- Can be shed - cells fall off a surface
- Can be scraped off a surface
Give 4 examples of fluids that cells are shed into
What is the problem with using cells that have been shed in diagnosis?
Cells usually degenerate, so cancer pick-up rate is low
How does the pick-up rate of cancer differ between shed cells and scraped cells?
The scraped cells are intact and viable, so the pick-up rate is higher
When is an aspirate sample taken?
When no surface is available for exfoliation
Give 3 locations that an aspirate sample would be taken from
- Accessible lump
- Lymph node
How is an aspirate sample collected? al
With a needle into a lump, free hand - without guidance
How is an aspirate sample collected?
Under imaging guidance
Give three locations where an aspirate sample would be obtained
- Inaccessible lump
What is initially reported on when a histologist obtains a specimen?
A macroscopic description of;
Why is tissue resected during cancer surgery inked?
To demonstrate the excision margin when you look at it down the microscope
What happens if a cancer extends to the excision margin?
Probably need further treatment
How is the tumour specimen further divided from its original form?
Blocks are taken from areas of interest
What happens to the tissue blocks cut from the specimen?
They are impregnanted with wax to support tissue, and 4μm sections are cut
How are the 4μm sections prepared for microscope visualisation?
They are mounted on a glass slide and stained