Neoplasms 1 Flashcards
What is a neoplasm?
An abnormal growth of cells that persists after the initial stimulus is response
What must be true for a neoplasm to grow without continuation of the stimulus?
Some degree of autonomous growth
What is a malignant neoplasm?
A neoplasm that invades the surrounding tissue with the potential to spread to a distant site
Is hyperplasia reversible?
Yes
What causes neoplasia?
Genetic alterations
It neoplasia reversible?
No
What is a tumour?
Any clinically detectable lump or swelling
Is a neoplasm a tumour?
Yes, but just one type
What is a cancer?
Any malignant neoplasm
What is a metastasis?
A malignant neoplasm that has spread from its original site to a new non-contiguous site
What must be true of the spread of a malignant neoplasm?
It cannot be due to direct spread, it must have some sort of transport mechanism
What is the primary site?
The original location of the tumour
What are the places a cancer has spread to called?
Secondary sites
What is dysplasia?
A pre-neoplastic alteration in which cells show disordered tissue organisation
Why is dysplasia not neoplastic?
Because the change is reversible
What can dysplasia lead to?
Neoplasia
What is the difference between benign and malignant neoplasms?
They show different behaviour
What behaviour do benign neoplasms show?
They remain confined to their site of origin, and do not produce metastases
Are benign neoplasms symptomatic?
They may or may not be, depending on location
When may benign neoplasms cause symptoms?
If at a critical site, for example a small space
What do malignant neoplasms have the potential to do?
Metastasise
What is the problem with malignant neoplasms metastasising?
There is an ever increasing tumour burden, the tumour spreads to make new tumours, which then have the potential to make new tumours too
What do benign tumours do?
Push and squash
What do malignant tumours do?
Invade and destroy
How do benign tumours appear to the naked eye?
They grow in a confined local area and so have a pushing outer margin
How do malignant tumours appear to the naked eye?
They have an irregular, jagged outer margin and may show areas of necrosis and ulceration (if on surface)
Why do malignant tumours show areas of necrosis?
Often, bits of tumour are growing faster than the blood supply, so undergo ischaemic death
Why do malignant tumours cause ulceration?
They cause a break in the surface
What do neoplasms show under the microscope?
Varying degrees of differentiation
How do benign tumours appear under the microscope?
They have cells that closely resemble the parent tissue, i.e. they are well differentiated
How do malignant neoplasms appear under the microscope?
They range from well to poorly differentiated
What are cells that have no resemblance to any tissue called?
Anaplastic
What happens to cells with worsening differentiation?
They have increasing nuclear size and nuclear to cytoplasmic ratio
Increased nuclear staining
More mitotic figures
Increasing variation in size and shape of cells and nuclei
What does an increase in nuclear size reflect?
A change in chromosomes
What is increased nucleur staining known as?
Hyperchromasia
What is a variation in size and shape of nuclear staining called?
Pleomorphism
How do clinicians indicate differentiation?
In grades, with high grade being poorly differentiated
What does dysplasia represent?
Altered differentiation
What indicates worsening differentiation?
Mild, moderate and severe dysplasia
What is neoplasia caused by?
Accumulated mutations in somatic cells
What are mutations caused by?
Initiators and promoters
What are initiators?
Mutagenic agents
What do promoters cause?
Cell proliferation
What do initiators and promotes result in, in combination?
An expanded, monoclonal population of mutant cells
What are the main initiators?
Chemicals
Infections
Radiation
Can chemicals, infections and radiation act as promoters?
Some can
How can mutations be obtained in some neoplasms?
Inherited, rather than from an external mutagenic agent
How does a neoplasm emerge from a monoclonal population?
Through a process called progression
What is progression characterised by?
Accumulation of yet more mutations
When is a collection of cells monoclonal?
If they all originated from a single founding cell
Where does evidence that neoplasms are monoclonal come from?
The study of the X-linked gene for the enzyme glucose-6-phosphate dehydrogenase (G6PD) in tumour tissue in women
How does the G6PD gene provide evidence that neoplasms are monoclonal?
The gene has several alleles encoding different isoenzymes. Early in female embryogenesis, one allele is randomly inactivated in each cell (lyonisation). In heterozygous women that happen to have one allele encoding a heat stable isoenzyme and one heat lable isoenzyme, normal tissue will be a patchwork of each type. However, neoplastic tissues only express on isoenzyme indicating a monoclonal group of cells
What do genetic alterations affect?
Proto-oncogenes and tumour supressor genes
What happens to proto-oncogenes that causes neoplasms?
They become abnormally activated
What are proto-oncogenes called when they are activated?
Oncogenes
What do tumour suppressor genes normally do?
Suppress neoplasm formation
What happens to tumour suppressor genes that causes neoplasms?
They become inactivated
What does the organised system for naming neoplasms take into account?
A neoplasms site of origin, wether it is benign or malignant, the type of tissue the tumour forms and sometimes the gross morphology (e.g. a cyst or papilloma_
What do benign neoplasms end in?
NAME?
What do malignant neoplasms end in?
-carcinoma if its epithelial
-sarcoma if its a stromal malignant neoplasm
What % of malignant tumours are epithelial?
90%
What can carcinomas be?
In situ
Invasive
What is meant by a tumour being in situ?
There is no invasion through the basement membrane
What is meant by a tumour being invasive?
It has penetrated through the basement membrane
What is leukaemia?
A malignant neoplasm of blood-forming cells arising in the bone marrow
What are lymphomas?
Malignant neoplasms of lymphocytes, mainly affecting lymph nodes
What is myeloma?
A malignant neoplasm of plasma cells
What do germ cells neoplasms arise from?
Pluripotent cells, mainly in the testis or ovary
What do neuroendocrine tumours arise from?
Cells distributed throughout the body
Who do -blastomas mainly occur in?
Children
What are -blastomas formed from?
Immature precursor cells
