Lab Diagnosis of Cancer Flashcards
(48 cards)
What is the gold standard for cancer diagnosis?
Histology
What proportion of cases show histological features at either end of the benign-malignant spectrum?
The majority
What produces problems of diagnosis and management?
The small number of cases that sit in the middle of the spectrum that are difficult to classify
What types of tissue samples are sent for cancer diagnosis?
- Diagnostic biopsy (incisional/needle core)
- Excisional specimen (can be done with curative intent)
What types of cytology samples are sent for cancer diagnosis?
- Exfoliative (scraped or shed cells)
- Fine needle aspiration +/- US guidance
What samples can be taken of shed cells?
- Sputum
- Urine
- Pleural fluid
- Ascites
What is the issue with samples of shed cells?
Cells degenerate quickly so cancer pick-up rate is low
What samples can be taken of scraped cells?
- Cervical smear
- Bronchial brushings
Why are scraped cells better than shed cells?
Cells are intact and viable so cancer pick-up rate higher
When do you take an aspirate?
When no surface is available:
- Accessible lump
- Breast tissue
- Lymph node
When is US guidance needed?
For an aspirate of an inaccessible lump, the liver or pancreas
How are tissue samples processed?
Tissue blocks are impregnated with wax to support the tissue while 4µm sections are cut.
These sections are mounted on a glass slide and stained.
What is the major stain used in histology?
H&E (Haemotoxylin and Eosin)
What will a histology report consider? (6)
- Is there a lesion (sampling error)?
- Is it malignant?
- What kind of malignancy is it?
- Grade?
- Stage?
- Has it all been removed?
What 2 criteria are taken into consideration when judging if a lesion is malignant?
- Tissue changes
- Cytological changes
What tissue changes are considered when judging malignancy?
- Dysplasia
- Invasion
- Infiltrative margin
What cytological changes are considered when judging malignancy?
- Nuclear pleomorphism, size, shape and staining
- Increased proliferation, number mitotic figures
- Abnormal mitotic figures
What is judged when classifying the type of malignancy?
- Identifying differentiation (histogenic classification)
- Molecular classification (esp. with HPV)
- Architectural arrangement
- Cytological differentiation
What are the classes of tissues that can be distinguished in histogenic classification?
- Squamous
- Glandular
- Lymphoid
- Melanocytic etc
What can be looked at in cytological differentiation to judge what sort of malignancy is present?
- Morphology
- Protein expression
What is the grade of a tumour?
How well differentiated it is from the original tissue
What does grade indicate?
Management and sometimes prognostication
What does well differentiated mean?
The tumour cells closely resemble the original tissue. Likely to be indolent/less agressive than a poorly differentiated tumour.
How is grade assessed?
- Proliferation
- Architectural differentiation
- Pleomorphism
