Flashcards in MOD 8 Deck (91)
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 surrounding tissue with potential to spread to distant sites.
Define a tumour:
Any clinically detectable lump or swelling (cancer is just one type of tumour).
Any malignant neoplasm.
A malignant neoplasm that has spread from its original site (primary site) to a non-contiguous site (secondary site).
What is dysplasia?
A pre-neoplastic alteration in which the cells show disordered tissue organisation. It is not neoplastic because change is reversible.
How does the gross morphology of benign and malignant neoplasms differ?
Benign neoplasms grow in a confined area and so have a pushing outer margin (this is why they are so rarely dangerous). This results in them pushing and squashing surrounding tissue into a pseudocapsule of compressed tissue. Malignant tumours have an irregular outer margin and shape and may show areas of necrosis and ulceration (if on a surface). They are attached to the surrounding tissue and therefore are not mobile.
What are 'initiators' of neoplasms? Give some examples of 'initiators':
Mutagenic agents that cause mutations that lead to neoplasms e.g. chemicals, infections and radiation.
What are 'promoters' of neoplasms? Give some examples of 'promoters':
A substance, though not mutagenic itself, aids in neoplasm formation by causing cell proliferation. Though some substances act as both initiators and promoters.
What is the result of the action of initiators and promoters combined? How does this ultimately result in a neoplasm?
They produce an expanded monoclonal population of mutant cells. Neoplasms emerge from this population through a process called 'progression', characterised by the accumulation of yet more mutations.
Are mutagens the only cause of mutations that cause neoplasm?
No, some neoplasm mutations are caused by inherited rather than external mutagenic agents.
What does a monoclonal population of cells mean?
That that population of cells all originated from a single founding cell.
Describe some evidence that neoplasms consist of a monoclonal cell population.
In female embryogenesis, one of their X chromsomes is randomly inactivated in each cell (Lyonisation). On the X chromosome is a gene for G6PD which has various isoforms. In heterogenous woman with a heat stable and heat labile isoform of this gene, normal tissues will have a patchwork of each type of gene whereas neoplastic tissue only expresses one genotype.
Mutation of which types of genes leads to the formation of a neoplasm?
Proto-oncogenes (abnormal activation) and tumour suppresser genes (inactivation).
What are abnormally activated proto=oncogenes called?
What is the suffix that tends to be used for benign neoplasms?
What is the suffix that tends to be used for malignant neoplasms?
1. -carcinoma (if it is an epithelial malignant neoplasm)
2. -sarcoma (if it is a stomal malignant neoplasm)
How many malignant tumours are carcinomas?
What is the difference between in-situ and invasive carcinomas?
In-situ carcinomas have not invaded through the epithelial basement membrane whereas invasive have.
What is leukaemia?
A malignant neoplasm of blood-forming cells arising in the bone marrow.
What are lymphomas?
Malignant neoplasms of lymphocytes that mainly affect lymph nodes.
What is myeloma?
A malignant neoplasm of plasma cells.
What type of cell do germ cell neoplasms arise from? Where are they mainly found?
From pluripotent cells, mainly in the testis or ovary.
Where do neuroendocrine tumours arise from?
Cells distributed throughout the body.
What does the suffix -blastoma mean?
It is used to describe neoplasms which mainly occur in children and are formed from immature precursor cells e.g. nephroblastoma.
What is the difference between hyperplasia and neoplasia?
They both can consist of an abnormal growth of cells, however neoplasia PERSISTS after the initial stimulus is removed, whereas hyperplasia is reversible.
Give some examples of non-neoplastic tumours:
What behvioural changes can be seen with a frontal brain tumour?
Heightened sexualised behaviour.
Cells with no resemblance to any tissue. There has been loss of differentiation of these cells and their orientation to each other.