Pathology - Neoplasia 1 Flashcards
What is a neoplasm?
An abnormal growth of cells that persists after the initial stimulus is removed (in malignant neoplasms, it also invades surrounding tissue with potential to spread to distant sites)
What is a tumour in general terms?
Any clinically detectable lump or swelling
What is the difference between a cancer and a neoplasm?
A neoplasm is just one type of tumour, while a cancer is any malignant neoplasm
What is a metastasis?
A malignant neoplasm which has spread from its original site to a new, non-contagious site. The original location is the primary site, and the place it spread to it the secondary site.
What is dysplasia?
A pre-neoplastic alteration in which cells show disordered tissue organisation. Its ‘pre-neoplastic’ because the change is reversible
True or false - a benign neoplasm can produce metastases?
False - only malignant neoplasms can metastasise
What is the difference in shape between benign and malignant neoplasms?
Benign tumours grow in a confined local area and therefore have a ‘pushing outer margin’ and squash the surrounding tissue. Malignant tumours have an irregular outer margin/shape, and may show areas of necrosis and ulceration
What does it mean if a neoplasm is ‘well differentiated’?
It has cells that closely resemble the parent tissue. Benign neoplasms are all well differentiated, while malignant ones range from well to poorly differentiated.
What is an anaplastic cell?
Cells with no resemblance to any tissue
What are the features of worsening differentiation?
- increasing nuclear size and nucleus:cytoplasm ratio
- increased nuclear staining (hyperchromasia)
- more mitotic figures
- increasing variation in size and shape of cells and nuclei (pleomorphism)
What does ‘grade’ refer to in neoplasm?
It indicates the degree of differentiation, with high grade being poorly differentiated. ‘Dysplasia’ can also be used as a measure for this
What causes the mutation seen in neoplasia?
Initiators (mutagenic agents, eg chemicals, infection and radiation) and promoters (cause cell proliferation)
True or false - neoplasms are monoclonal?
True - they all originate from a single founding cell.
How do we know that neoplasms are monoclonal?
A study of the X-linked gene for the enzyme G6P-dehydrogenase in tumour tissue from women. The gene has several alleles encoding different isoenzymes. Early in female embryogenesis one allele is randomly inactivated in each cell (Lyonisation). 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
How do genetic alterations affect proto-oncogenes?
The become abnormally activated (are then called ‘oncogenes’) and favour neoplasm formation.
