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
What are the suffixes for tumours derived from epithelial tissue?
Malignant= -carcinoma Benign= -oma
What are the prefixes used for classification of the different types of epithelial neoplasms?
Protective epithelium: Benign= Papill- Malignant= Squamous cell- Basement epithelium: Basal cell- Secreting epithelium: adeno-
What is the suffix used for neoplasms of connective tissue?
Malignant= sarcoma Benign= oma
What are the prefixes for neoplasms in connective tissue?
Fibrous= fibro nerve sheath= neurofibro adipose= lipo smooth muscle= leiomyo striated muscle= rhabdomyo Cartilage= chondro Bone/Oestoblast= osteo
What are the different types of tumours from lymphoid and haempoietic cells?
Malignant lymphoma
Multiple myeloma
Hodgkins disease
Leukaemia
What is the term used for neoplasms which arise from more than one germ layer and cell type?
Tetratomas
What are blastomas?
Neoplasms that resemble primitive embryonic tissues
Why is invasion of tumours easy to recognise/
There is erosion of the basement membrane
What are the three steps in metastases?
Tumour cell invasion of blood vessels
Embolization
Extravastion from the vessel
What is the barrier to tumour cell invasion and how is this overcome by tumour cells?
The barriers are the basement membrane and stromal extracellular matrix
These are overcome by detachment of the tumour cell from the original tumour, degradation of the basement membrane matrix, locomotion and infilatration of tumour cells,, degradation of extracellular and vascular matrix
How do neoplastic cells invade surrounding tissue?
Gain of motility
Loss of mechanism of contact inhibition
secretion of proteolytic enzymes
The process of cell locomotion is combined with matrix degradation repeatedly to allow continued invasion of tissue
What are the three routes by which malignant tumours spread?
Blood vessels, lymphatics and transcoelemic
Or can be transplanted by seeding from physical contact if correct practice is not followed during surgical treatment
What occurs in metastasis via the blood?
Secondary tumours occur in organs which are perfused by blood drained from the tumour, commonly infects bone, liver, lung and brain
What occurs in lymphatic metastasis?
Tumour cells sette and grow on the periphery of lymphnodes resulting in a node which feels firmer and larger than normal as well as oedama of the surrounding tissue due to poor drainage
What occurs in transcoelomic metastasis?
Effusion into the body cavities (pritoneal, pleural, pericardial) cells grow as nodules on mesothelial surface of cavity
What does the stage of a tumour measure?
The spread of the malignant tumour, determined by the TMN system
How does the TMN system work?
T= size and extent of invasion by tumour
N=Node indicates extent of lymph node involvement
M= Metastases= indicates if distant metastases
What is microinvasion?
Spread of epithelial malignancies ust beyond the point of origin through the basement membrane
What is an In-situ tumour?
Epithelial malignancy confined to just the epithelium as it has not yet gone through the basement membrane
What is local invasion?
Spread within the organ of origin
What are local metastases?
Spread to the lymph nodes closest to the organ of origin
What is indicated by distant metastasis?
Spread to other organs or distant lymph nodes
What are the different T stages?
Tis= In-situ, non invasive T1= Small, minimally invasive within primary organ site T2= Larger more invasive within primary organ site T3= Larger more invasive beyond margins of primary organ site T4= Very large, adnd very invasive with spread to adjacent organs
What are the different N stages?
N0= No lymph node involvement N1= Regional lymphnode involvment N2= Extensive regional lymph node involvement N3= More distant lymph node involvement
What are the different M stages?
M0= not distant metastases M1= Distant metastases present
What is the basis for grading of tumours?
Microscopic appearance of neoplasm via H and E staining, determination of resemblance of the tumour cell and its parent cell as a measure of aggressiveness
What are the different grades of tumour cells?
G1= Well differentiated looking very similar to normal tissue G2= Moderately differentiated looking something like normal G3= Poorly differentiated, hardly looks like normal tissue G4= anaplastic having no similarity to any normal tissue
