Lecture 26 Flashcards
What is the key difference between for neoplasia and metaplasia?
Metaplasia is a reversible change while neoplasia is an irreversible change
What three key features of neoplasms?
Increased cell proliferation, alered cell differentiation, altered relationship with stroma
What are the consequences of the increased cell proliferation seen in neoplasms?
A large number of cell of one type are on a small location known as a focus, if this is an anatomically inappropriate position it can be damaging
What are the effects of the altered cell differentiation seen in neoplasms?
Neoplasia typically undergo de-differentiation where previously silenced embryonic genes and mutated genes are expressed
This can also result due to impaired differentiation although this is very rare
What are the effects of the altered relationship with the stroma seen in neoplasms?
Results in uncontrolled growth, where the neoplastic cells invade the surrounding tissue and recruit this tissue to provide nutrients and blood via angiogenesis
What are the four things that are considered when classifying a neoplasm?
The aetiology, organ of origin, biological behavior of the neoplasm and the tissue or cell of origin
How is aetiology considered when classifying a neoplasm?
This is often unknown and therefore not very useful in classifying tumours
What are the two biological behaviours used in classification of neoplams?
Benign or malignant
How do benign tumours grow and how does this relate to their prognosis?
These tumours grow as compact mass, typically surrounded by a capsule this makes them non-invasive and often gives them a lower growth rate accounting for a better prognosis
What are the important features of benign tumours?
Do not invade the tissue Confined to site of origin Often form polyps in hollow organs Histologically resemblant of the parent cell (though differences are still there) Low growthrate with few mitotic cells
How do benign tumours cause damage?
Can cause pressure atrophy of surrounding parenchymal tissue, as well as obstructing fluid flow
What is the result of a benign meningeal tumour?
Epilepsy
What is the result of a benign thyroid tumour?
excessive production of thyroid hormone
What are the key pathological features of malignant tumours?
invade the surrounding tissue and grow in an irregular pattern
Spread via metastasis through the lymphatic or blood system
Cause considerable mortality and morbidity
Why do malignant tumours cause clinical problems?
Pressure and destructon of adjacent tissue Formation of secondary tumours Blood loss from ulcerated surfaces Obstruction of blood flow Inappropriate production of hormones pain
What is metastasis?
Formation of secondary tumours
What are the important features of malignant tumours?
Poorly circumscribed allowing for them to be highly invasive
Poor resemblance to parent cell
Often central necrosis
Often ulcerated surfaces
Why is classification by histo/cyto-genesis so challenging?
Due to the dedifferentiation which occurs to cells in neoplasms they are often so poorly differentiated no parent cell type is obvious