MoD 9 Neoplasia Flashcards
(40 cards)
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
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
How is the behaviour of benign and malignant neoplasms different?
Benign neoplasms remain confined to their site of origin while malignant neoplasms can metastasise
How are benign and malignant neoplasms different to the naked eye?
Benign grow in a confined local area and so have a pushing outer margin while malignant tumours have an irregular outer margin and shape and may show areas of necrosis and ulceration if on a surface
What type of cells do benign neoplasms have?
Cells closely resembling the parent tissue i.e. well differentiated
What type of cells do malignant neoplasms have?
Can range from well differentiated to poorly differentiated
What are anaplastic cells?
Cells having no resemblance to any tissue
What can be seen in poorly differentiated cells under the microscope?
Increasing nuclear size increasing nuclear:cytoplasmic ratio Nuclear hyperchromasia more mitotic figures increasing variation in shapes and size of cells and nuclei (pleomorphism)
How are neoplasms graded?
High grade poorly differentiated
Low grade well differentiated
G1, G2, G3
What can dysplasia mean other than abnormal development?
Altered differentiation. Mild, moderate and severe indicating worsening differentiation
What are the steps in worsening differentiation of skin?
Reversible change- dysplasia - loss of keratin and reduced specialisation
Irreversible- carcinoma in situ - basement membrane intact
Invasive carcinoma- tripolar mitosis, destruction of basement membrane
Is neoplasia caused by singular mutations?
No, accumulated mutations
What is an initiator?
Mutagenic agent
What is a promoter?
Agents causing cell proliferation
What combination of initiators and promoters causes mutation?
Initiator followed by prolonged promotion
What does the combination of initiators and promoters result in?
Monoclonal population of mutant cells
What are the main initiators?
Chemicals, infections and radiation
some of these can act as promoters too
Are mutations in neoplasms always from an external mutagenic agent?
No, sometimes germline mutation gives head start
What is progression?
the accumulation of more mutations in a monoclonal population causing a neoplasm
How do we know that neoplasms are monoclonal?
Study of X-linked gene for glucose-6-phosphate dehydrogenase (G6PD) in tumour tissue from women.
Early in embryogenesis one allele in each cell is inactivated randomly (lyonisation). Neoplastic tissues only express one isoenzyme indicating a monoclonal group of cells
Mutations in what two type of genes that regulate the cell cycle favour neoplasm formation?
Proto-oncogenes are activated to oncogenes
Tumour supressor genes become inactivated
A combination of numerous of each must mutate to cause neoplasms
