Neoplasia 1 Flashcards
Neoplasia
A lesion resulting from the autonomous or relatively autonomous abnormal growth of cells which persists after initialising stimulus removed
(can be benign or malignant)
What causes tumours?
Tumours arise due to accumulation of genetic alterations and epigenetic change
How do we know if growth is neoplastic?
Neoplasms comprise neoplastic cells plus connective tissue stroma
-vascular supply important
- Malignant
- Benign
- neoplasm with potentially lethal, abnormal characteristics which has the ability to invade and metastasise (Underwood)
- A neoplasm which does not have this ability
Exceptions to malignant and benign rule
- Some malignant tumours almost never metastasise (ie basal cell carcinoma)
- Some benign tumours can be very locally harmful/destructive
“Benign” does not always mean “harmless”
Main distinguishing features of neoplasm
- Differentiation
- Rate of growth
- Local Invasion
- Metastasis
Differentiation
extent to which neoplastic tissues resemble their corresponding normal tissue of origin
Well differentiated features
- Closely resembles normal tissue of origin
- Little or no of evidence of anaplasia
- Can be benign, or malignant
Poorly differentiated features
Little resemblance to tissue of origin
Undifferentiated / anaplastic features
-Cannot be identified by morphology alone
-May need special stains / molecular techniques to diagnose
Poor differentiation features
- Nuclear pleomorphism- Variability in nuclear size / shape
- Abnormal nuclear features
High nuclear : cytoplasmic ratio
Clumped chromatin
Prominant nucleoli - Increased mitotic activity
- Loss of cellular polarity / order
- Tumour giant cells
- Necrosis
Differentiation Summary: Malignant Vs Benign
Malignant:
Anaplastic features
Generally poorer differentiation
Benign:
Well differentiated
Close resemblance to tissue of origin
What’s GRADE of tumour?
Closely related to differentiation / clinical behaviour
A measure of how differentiated the tumour appears
Well differentiated = low grade / grade 1
Moderately differentiated = intermediate / grade 2
Poorly differentiated = high grade / grade 3
What’s STAGE of tumour?
A measure of extent of spread of a tumour
Prognostication / therapeutic decisions
The lower the number the better for the patient
Metaplasia
change in phenotype of differentiated cells, often in response to chronic irritation