MoD S9 - Neoplasm I Flashcards
Define ‘neoplasm’
An abnormal growth of cells that persist after the initial stimulus is removed
How does a malignant neoplasm differ from a benign neoplasm?
The malignant neoplasm invades surrounding tissue with potential to spread to distant sites (have the potential to metastasise), benign does not
Define ‘Tumour’
Give an example of a tumour
A tumour is any clinically detectable lump or swelling
E.g. A neoplasm
What is a cancer?
A malignant neoplasm
What is a metastasis?
A malignant neoplasm that has spread from its original site to a non-contiguous site
The original site is the primary site
The metastasis is a secondary site
How does dysplasia relate to neoplasm?
Give a difference between the two
A pre-neoplastic alteration in which cells show disordered tissue organisation
Dysplasia is not neoplastic change as it is reversible
What are the two major types of tumour?
Non-neoplastic (E.g. Abscess,haematoma)
Neoplastic (benign, malignant)
What are the differences in benign and malignant neoplasm to the naked eye?
Benign tumours grow in a confined local area and so have a pushing outer margin (This is why they’re so rarely dangerous)
Malignant tumours have an irregular outer margin and shape and show areas of necrosis and ulceration (if on surface)
What are the differences in benign and malignant neoplasm under the microscope?
Malignant:
- Neoplasms are well to poorly differentiated
- Increasing nuclear size and nuclear to cytoplasmic ratio
- Nuclear hyperchromasia
- Higher mitotic count, may be abnormal
- Increased size and shape variance of cells and nuclei (pleomorphism)
Benign :
- Neoplasms closely resemble patient’s tissue (i.e. well differentiated)
- Minimal pleomorphism
- Lower mitotic count, mitoses are normal
What is meant by the term ‘anaplastic’?
Where do anaplastic cells occur?
Cells with no resemblance to any tissue are called anaplastic
Occur in malignant neoplasm
How is level of differentiation of a tissue rated?
What clinical outcome does differentiation correlate with?
Tissue given a grade G1 to G3
G3 is poorly differentiated, G1 is well differentiated
Higher grade has lower 5 year survival rate
What is the cause of neoplasia?
Accumulated mutations in somatic cells
Mutations are caused by:
- Initiators, which are mutagenic agents
- Promoters, which cause cell proliferation
What are the main initiators?
Chemicals
Infections
Radiation
Some also act as promoters
When promoters and initiators work in tandem on cells what is the result?
An expanded monoclonal population of mutant cells (mutations caused by initiators and promoters)
A neoplasm emerges from this population through a process known as progression, characterised by the accumulation of yet more mutation
How do we know neoplasms are monoclonal?
Study of X linked genes for the enzyme glucose-6-phosphate (G6P) dehydrogenase in tumour tissue from women
The gene has several alleles encoding different isoenzymes of the enzyme, In early female embryogenesis one allele is randomly deactivated (lyonisation)
In heterozygous women with one heat labile isoenzyme and one heat stable isoenzyme normal tissues are a patchwork of each type
Neoplastic tissues only express one isoenzyme indicating a monoclonal population
