8. Neoplasms Flashcards
What is a neoplasm?
An abnormal growth of cells that persists after the initial stimulus is removed.
What is a malignant neoplasm?
An abnormal growth of cells that persists after the initial stimulus is removed and invades the surrounding tissue with potential to spread to distant sites.
What is a tumour?
Any clinically detectable lump or swelling.
What is a cancer?
A malignant neoplasm.
What is a metastasis?
A malignant neoplasm that has spread from its original site to a new non-contiguous site.
What are the primary and secondary site of a metastasis?
Primary - original site.
Secondary - place where it spreads to.
What is dysplasia?
A pre-neoplasmic alteration in which cells show disordered tissue organisation, this is reversible.
What is the key difference between benign and malignant neoplasms?
Benign neoplasms remain confined to their site of origin and do not produce metastases. Malignant neoplasms have the potential to metastasise.
Why are benign tumours rarely dangerous?
Because they grow in a confined local area and so have a pushing outer margin.
What is the outer margin and shape of malignant tumours?
Irregular.
How do malignant tumours cause necrosis and ulceration?
Necrosis by the tumour growing faster than the blood supply so ischaemic death.
Ulceration - irregular outline breaks epithelia.
How well differentiated are benign and malignant neoplasms?
Benign are well differentiated.
Malignant can be well differentiated or anaplastic - so poorly differentiated that they have no resemblance to any tissue.
What are some microscopic features of worsening differentiation?
Increasing nuclear size and nuclear to cytoplasmic ratio, increased nuclear staining (hyperchromasia), more mitotic figures and increasing variation in size and shape of cells and nuclei (pleomorphism).
What do grades indicate?
Levels of differentiation, high grade = poorly differentiated.
What is dysplasia?
Represents altered differentiation.
What percentage of cancer risk is down to environmental or extrinsic factors?
85%.
What are mutations caused by?
Initiators (mutagenic agents), and promoters (cause cell proliferation).
What does a combination of initiation and promoters lead to?
A monoclonal population of mutant cells.
What is the process progression?
The way by which a neoplasm emerges. It’s from the accumulation of yet more mutations.
What proof is there for neoplasms being monoclonal?
A study of the X-linked gene for the enzyme glucose-6-phosphate dehydrogenase (G6PD) in tumour tissue from women gave evidence. The gene has several alleles encoding different isoenzymes. Early in female embryogenesis one allele is randomly inactivated in each cell. In heterozygous women that happen to have one allele encoding a heat stable isoenzyme and one a heat labile isoenzyme, normal tissues will be patchwork of each type. However, neoplastic tissues only express one isoenzyme indicating a monoclonal group of cells.
What happens to proto-oncogenes when genetically altered?
They become abnormally activated, permanently switched on. They’re now classed as oncogenes.
What happens to tumour suppressing genes when they are genetically altered?
They become inactivated so can’t do their usual role of suppressing neoplasm formation.
What does the organised system of naming neoplasms take into account?
Neoplasm’s site of origin, whether it’s benign or malignant, the type of tissue the tumour forms and sometimes gross morphology.
What do the names of benign and malignant neoplasms end in?
Benign -oma.
Malignant -carcinoma if epithelial malignant neoplasm (90% of malignant neoplasms). Or -sarcoma if stromal malignant neoplam.
What is the difference between in-situ and invasive?
In-situ = no invasion of epithelial basement membrane. Invasive = penetrated through basement membrane.
What is leukaemia?
A malignant neoplasm of blood-forming cells arising int he bone marrow.
What are lymphomas?
Malignant neoplasms of lymphocytes, mainly affecting lymph nodes.
From what do germ cell neoplasms arise?
Pluripotent cells, mainly testis or ovary.
Where do neuroendocrine tumours arise from?
Cells distributing the body.
What are benign neoplasms of stratified squamous epithelia called?
Squamous papilloma. Any tumour with finger-like projections.
What are benign neoplasms of transitional epithelia called?
Transitional cell papilloma.
What are benign neoplasms of glandular epithelia called?
Adenoma.
What are malignant neoplasms of stratified squamous called?
Squamous cell carcinoma.
What are malignant neoplasms of transitional epithelia called?
Transitional cell carcinoma.
What are malignant neoplasms of glandular epithelia called?
Adenocarcinoma.
What are malignant neoplasms of other epithelia called?
Basal cell carcinoma, e.g. skin.
What are the two types of lymphoid neoplasms?
Hodgkins disease and non Hodgkins lymphoma.
Where do hamatopoietic neoplasms occur?
In bone marrow and abnormal cells enter blood.
What is the germ cell neoplasm of the testis?
Malignant teratoma, seminars.
What is the germ cell neoplasm of the ovary?
Benign teratoma - dermoid cyst.
What are some examples of neuroendocrine tumours?
Carcinoid tumours, phaeochromocytoma, small cell carcinoma of bronchus.
