Session 8 Flashcards
Define neoplasia
An abnormal growth of cells that persists after the initial stimulus is removed
Define 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 tumour
Any clinically detectable lump or swelling
Define cancer
Any malignant neoplasm
Define metastasis
A malignant neoplasm that has spread from its original site (primary site) to a new non-contiguous site (secondary site)
Define dysplasia
A pre-neoplasticism alteration in which cells show disordered tissue organisation (reversible)
Compare dysplasia and neoplasia
Neoplasia = irreversible
Dysplasia = reversible
Do benign neoplasms produce metastases?
No - remain confined to their site of origin
Describe the appearance of a benign neoplasm to the naked eye with regards to its outer margin in particular
Has a regular ‘pushing’ outer margin and grows in a confined area
Benign neoplasms may push on local structures causing…
Inflammation
Describe the appearance of cells of a benign neoplasm under the microscope
Cells closely resemble the parent tissue - well differentiated
Do malignant neoplasms have the potential to metastasise?
Yes, by definition
Describe the appearance of a malignant neoplasm to the naked eye
Irregular outer margin and shape
May show necrosis/ulceration
Describe the appearance of the cells of a malignant neoplasm under a microscope
Cells range from well to poorly differentiated
What is meant by the term anaplastic?
Cells have no resemblance to any tissue
Compare the cells seen in malignant neoplasms with the cells seen in benign neoplasms
Benign - well differentiated cells (resemble parent tissue)
Malignant - poorly to well differentiated (a range)
Describe the varying degrees of differentiation seen in benign and malignant neoplasms under the microscope
Benign - cells well differentiated, closely resemble parent tissue
Malignant - cells range from well to poorly differentiated
Name 5 changes seen in cells due to worsening differentiation as seen in malignant neoplasms
Nuclear hyperchromasia
Increased nuclear:cytoplasm ratio
Increased mitoses (mitotic figures)
Larger nucleus
Cellular and nuclear size variation (pleomorphism)
What is nuclear hyperchromasia?
Increased nucleus staining due to increased DNA content
Clinicians use the term __________ to indicate differentiation
Grade
Clinicians use the term grade to indicate differentiation.
High grade = _________ differentiated
Poorly
Neoplasm is caused by an accumulation of _____________ in somatic cells
Mutations
What sort of factors are the most important causes of mutations?
Extrinsic/Environmental Factors
Mutations are caused by initiators and promoters.
What is the function of an initiator?
What is the function of a promoter?
Mutagenic agent - introduces mutation
Causes cell proliferation
Mutations are caused by initiators and promoters. In combination they result in…
An expanded, monoclonal population of mutant cells
Name the three main initiators of neoplasia
Infections
Chemicals
Radiation
A neoplasm emerges from a monoclonal population through a process called _______________ where there is an accumulation of ______________
Progression
Mutations
What is meant by the term monoclonal with regards to a cell population?
A collection of cells that all originated from a single founding cell
What is evidence that neoplasms are monoclonal?
From the study of x-linked gene for the enzyme G6PD in tumour tissue from women
Evidence from the study the of x-linked gene for the enzyme _________ in tumour tissue from women supports the theory that neoplasms are monoclonal
G6PD
Describe how the study of the x-linked gene for G6PD in tumour tissue from women provides evidence that neoplasms are monoclonal
Gene has several alleles encoding different isoenzymes
Early in embryogenesis one allele is randomly inactivated in EACH cell (lyonisation)
In women that have alleles coding for different isoenzymes, normal tissue will be a patchwork of each
In neoplastic tissues only one isoenzyme is expressed —> indicating monoclonal group
What is lyonisation? With regards to G6PD?
Random inactivation of the allele from one x chromosome
Early in embryogenesis, one allele coding for G6PD is randomly inactivated
Genetic alterations in neoplasms affect which two types of genes?
Proto-oncogenes
Tumour suppressor genes
Proto-oncogenes become abnormally activated forming…
Oncogenes
The formation of oncogenes from proto-oncogenes favours…
Neoplasm formation
In neoplasia, tumour suppressor genes which normally suppress neoplasm formation become…
Inactivated
The system for naming neoplasms can take into account (4)
Site of origin
Malignant or benign
Type of tissue that the tumour forms
Gross morphology (cyst or papilloma)
Benign neoplasms end in…
-oma
Malignant neoplasms end in -carcinoma if it is…
Epithelial
Malignant neoplasms end in -sarcoma if it is…
Stromal
-blastomas mainly occur in ____________ and are formed from…
Children
Immature precursor cells
The majority of malignant neoplasms are of which type? Give a rough percentage.
Carcinomas (epithelial origin)
~90%
Why are carcinomas more common than sarcomas?
Epithelial cells are at the surface and rapidly turnover so are more likely to be mutated
Carcinomas can be either… (2)
In-situ
Invasive
Compare an in-situ carcinoma with an invasive carcinoma
In-situ - no invasion of epithelial basement membrane
Invasive - penetrated through basement membrane
Is leukaemia malignant or benign?
Is lymphoma malignant or benign?
Malignant
Malignant
What type of cancer is leukaemia? Which cells are affected? Where does it arise?
MALIGNANT neoplasm affecting BLOOD-FORMING CELLS arising in the BONE MARROW
What type of cancer is lymphoma? What cells does it affect? What part of the body does it mainly affect?
MALIGNANT neoplasm affecting lymphocytes. Mainly affects lymph nodes.