Neoplasm Flashcards
What is a neoplasm
neoplasm is, “!n abnormal growth of cells that persists after the initial stimulus is removed”; For malignant neoplasms the definition needs extending: “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
A tumour is any clinically detectable lump or swelling. A neoplasm is just one type of tumour
What is a cancer
A cancer is any malignant neoplasm
What is a metastasis
A metastasis is a malignant neoplasm that has spread from its original site to a new non-contiguous site. The original location is the primary site and the place to which it has spread is a secondary site.
What is dysplasia?
Dysplasia is a pre-neoplastic alteration in which cells show disordered tissue organisation. It is not neoplastic because the change is reversible.
What is the different between benign and malignant neoplasms?
BENIGN AND MALIGNANT NEOPLASMS SHOW DIFFERENT BEHAVIOUR: 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?
BENIGN AND. MALIGNANT NEOPLASMS APPEAR DIFFERENT TO THE NAKED EYE: Benign tumours grow in a confined local area and so have a pushing outer margin. This is why they are so are rarely dangerous. Malignant tumours have an irregular outer margin and shape and may show areas of necrosis and ulceration (if on a surface)
How do neoplasms look under the miscroscope?
1.5 UNDER THE MICROSCOPE NEOPLASMS SHOW VARYING DEGREES OF DIFFERENTIATION: A benign neoplasm has cells that closely resemble the parent tissue, i.e. they are well differentiated. Malignant neoplasms range from well to poorly differentiated. Cells with no resemblance to any tissue are called anaplastic.
What are hyperchromasia and pleomorphism?
With worsening differentiation individual cells have 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, which is called pleomorphism.
What does grade mean?
Clinicians use the term grade to indicate differentiation, high grade being poorly differentiated. Ow grade = well differentiated Eg. 1-tubules 2-mitosis 3-nuclear pleomorphism
What does dysplasia Indicate?
Dysplasia also represents altered differentiation. Mild, moderate and severe dysplasia indicates worsening differentiation
What is neoplasia caused by?
1.6 NEOPLASIA IS CAUSED BY ACCUMULATED MUTATIONS IN SOMATIC CELLS:
The mutations are caused by initiators, which are mutagenic agents, and promoters, which cause cell proliferation.
What do initiators and promoters cause?
In combination initiators and promoters result in an expanded, monoclonal population of mutant cells. Chemicals, infections, and radiation are the main initiators but some of these agents can also act as promoters. In some neoplasms mutations can be inherited rather than from an external mutagenic agent.
What is progression?
A neoplasm emerges from this monoclonal population through a process called progression, characterised by the accumulation of yet more mutations. See Neoplasia Lecture 3
New mutations - cause new expansions
When we get enough mutations that cause dysreulated autonomous growth - neoplasm
We need initiation, promotion, and progression to make a cancer
What are protooncognees and oncogenes
Pathway taht impinges on the cell cycle. The genes that are important In cancer are genes involved in such pathways. Eg a gene coding for a receptor in thei pathway
Normal gene = protooncogene
Abnormally activated to drive proliferation = oncogene
How do we know neoplasms are monoclonal?
HOW DO WE KNOW NEOPLASMS ARE MONOCLONAL? A collection of cells is monoclonal if they all originated from a single founding cell. Evidence that neoplasms are monoclonal came from the study of the X-linked gene for the enzyme glucose-6-phosphate dehydrogenase (G6PD) 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
What do genetic alterations affect?
GENETIC ALTERATIONS AFFECT PARTICULAR TYPES OF GENE: Genetic alterations affect proto-oncogenes and tumour suppressor genes. Proto-oncogenes become abnormally activated (when they are then called oncogenes), favouring neoplasm formation. Tumour suppressor genes, which normally suppress neoplasm formation, become inactivated.
What does the explain naming system take into consideration?
The organised s ystem takes into account a neoplasm’s site of origin, whether it is benign or malignant, the type of tissue the tumour forms and sometimes the gross morphology (e.g. cyst or papilloma).
How are benign neoplasms named?
-Oma
Hoe are malignant neoplasms named
-carcinoma if it is an epithelial malignant neoplasm, which constitute 90% malignant tumours, or –sarcoma if it is a stromal malignant neoplasm
What is teh difference between in situ and invasive?
. Carcinomas can be in-situ (no invasion through epithelial basement membrane) or invasive (penetrated through basement membrane).
Is neoplasia reversible?
Dysplasia = reversible but neoplasia = irreversible
What is the difference between primary and secondary malignant neoplasia?
Secondary = metastasis
What is leukaemia?
Leukaemia is a malignant neoplasm of blood-forming cells arising in the bone marrow
