Neoplasia Flashcards
Define tumour
A swelling- any clinical detectable lump or swelling
Define neoplasm
An abnormal growth of cells that persists after the initial stimulus is removed.
Define oncology
Study of tumours and neoplasms
Define benign neoplasms
Gross and microscopic appearances are considered to be innocent , implying that it will remain localised and will not spread to other sites
Define cancer
A malignant neoplasm
Define malignant neoplasm
An abnormal growth of cells that persists after the initial stimulus has been removed and invaded surrounding tissue with the potential spread to distant sites
Define metastasis
Malignant neoplasm that has spread from its original site to a new non-contiguous site
What is dysplasia?
Pre-neoplasticism alteration in which cells show disordered tissue organisations.This is reversible.Cells in dysplasia can look malignant but they have not yet invaded. They exhibit considerable pleomorphism , with large hyperchromatic nuclei and high nuceleur to cytoplasmic ratios.
- Precursor to malignancy
This leads to carcinoma in situ where epithelial cells exhibit the same features as malignant cells ( the cells have not yet invaded the basement membrane). Therefore cells are NOT yet malignant.
What are the two branches of tumours ?
Non neoplastic ( eg abscess , haematoma)
Neoplastic ( can either be benign or malignant ( cancer ) . If it is malignant you need to consider whether it is primary or secondary ( metastasis)
Is neoplasia reversible ?
No it is irreversible
What is the difference between primary and secondary malignant neoplasm ?
Primary = the original location of the malignant neoplasm is the primary site
Secondary = the place to which it has spread is the secondary site
How can we tell the difference between a benign tumour and malignant tumour ?
- The behaviour of each tumour : benign neoplasms remain confined to their site of origin and do not produce metastases. Whereas malignant neoplasms invade and have the potential to metastasise. Also , as they grow in a confined local area they have a pushing outer margin. Whereas in malignant tumours they have an irregular outer margin and shape. They do not form a pseudo capsule the same way benign tumour does. Benign tumours grow slower than malignant tumours.
- Differences in appearances to the naked eye /microscope : benign tumours resembles tissues of origin , few mitosis m normal or mild increase in nuclear to cytoplasmic ratio. Cells are uniform throughout the tumour. Malignant tumours are the opposite.
- Differentiation : malignant tumours are poorly differentiation whereas benign tumours are well differentiated
Define differentiation
The process of becoming different by growth or development
Do benign neoplasms closely resemble their parents tissue or not ? What about malignant neoplasms ?
They closely resemble the parent tissue - considered to be well differentiated
Malignant neoplasms range from well to poor differentiated , dependant on how closely they resemble the cell of origin
What does anaplastic mean ?
Cells with no resemblance to any tissue
With worsening differentiation ( become more malignant ) how do the individual cells change ?
- Increase nuclear size
- Increased nuclear to cytoplasmic size
- Increased nuclear staining - become darker ( hyperchromasia )
- Increased mitotic figures
- Abnormal mitotic figures ( Mercedes Benz Sign )
- Variation in size and shape of cells and nuclei (pleomorphism )
What is a another term for a poorly differentiated tumour ?
A high grade tumour
Grade 1 to grade 3 ( gets worser )
Why do we get neoplasia ?
- Non-lethal genetic damage : genetic damage that can go unchecked by the cell cycle , by the immune system that can then proliferate.
A tumour is formed by the clonal expansion of the single precursor cells that has incurred genetic damage.
Genetic damage is caused by mutations which are caused by initiators called mutagenic agents
Give examples of mutagenic agents (initiators of mutations )
Chemicals : smoking , alcohol consumption , diet and obesity
Infectious agents : HPV
Radiation :
Inherited mutations eg BRACA1 BRACA2
Outline the general process by which a neoplasm forms
- You have a cell population which is stimulated by an initiator that causes a mutation.
- This cell then undergoes cell proliferation by promotors
- This continues to proliferate which causes a monoclonal collection of cells.
- The neoplasm then emerges from this monoclonal group of cells from a process called progression - this is characterised by the accusation of yet more mutations.
Which genes are affected by mutations ?
There are four classes of normal regulatory genes :
- Growth promoting proto-oncogenes : mutations that activate these generally cause an excessive increase in one or more normal functions. Once mutated they are now called ‘oncogenes ‘ which have the ability to promote cell growth in the absence of normal growth promoting cell signals. They are dominant over their normal counterparts ( only one gene needs to be mutated to have an effect )
- Growth inhibiting tumour suppressor genes : their normal function is to stop cell proliferation. A mutation in this causes a loss of function. Usually , both allles must be damaged for transformation to occur. Leads to failure of growth inhibition.
- Genes that regulate programmed cell death : enhances survival of cells
4, genes involved in DNA repair : impair the ability of the cell to recognise and repair non lethal genetic damage in other genes
NAMING NEOPLASMS : what do benign and malignant tumours end in ?
Benign tumours : end in ‘oma’
Malignant tumours : if epithelial (90% of the case )end in ‘ carcinoma ‘. And if Stromal they end in ‘ sarcoma ‘
If there is a benign epithelial neoplasm in stratified squamous epithelial cells , what will the neoplasm be called ?
Squamous papilloma ( has finger like projections)
Often in the buccal mucosa and skin.
If there was a benign neoplasm in transitional epithelium , what would the neoplasm be called ?
Transitional cell papilloma
Often found in bladder mucosa
