13. Neoplasia 1 Flashcards
Define neoplasm.
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 benign neoplasm
Gross and microscopic appearances that are considered to be innocent, implying that it will remain localised and will not spread to other sites
Define tumour.
Any clinically detectable lump or swelling
Define oncology
study of tumours and neoplasms
What is a cancer?
any malignant neoplasm
What is a metastasis?
Malignant neoplasm that has spread from its original site to a new non-contiguous site
What is the primary and secondary location of a cancer?
Primary: Original location of the malignant neoplasm
Secondary: place to which it has spread
What is dysplasia?
Pre-neoplastic alteration in which cells show disordered tissue organisation
Why is dysplasia not neoplastic?
The change is reversible in dysplasia whereas neoplasia is irreversible
What can displastic tumours exhibit?
Can exhibit considerable pleomorphism, with large hyperchromatic nuclei and high nuclear to cytoplasmic ratios
What are the 2 classifications of the causes of a tumour (swelling)?
- non-neoplastic
- neoplastic
Give examples of non-neoplastic tumours.
Abscess, haematoma
What are the two types of neoplastic tissues?
Benign
Malignant
What can a malignant tumour be divided into?
Primary and Secondary
What are the 3 ways in which benign and malignant are different?
- Behaviour
- Appear different to the naked eye
- Differentiation
What is the difference in benign and malignant neoplasm behaviours?
Benign neoplasms remain confined to their site of origin and do not produce metastases. Malignant neoplasms have the potential to metastasise.
How do benign neoplasms appear to the naked eye?
- Grow in a confined local area
- They have a pushing outer margin
- Rarely dangerous (location)
How do malignant neoplasms appear to the naked eye?
- Irregular outer margin and shape
- May have ulcerations and necrosis
- Infiltrative
What is a well differentiated neoplasm?
Mostly resembles normal tissue and usually has a good prognosis
What is a poorly differentiated neoplasm?
Doesn’t resemble normal tissue as well. Tumours spread easier than other tumours, and their prognosis is a worse than for others
What type of differentiation do benign neoplasms show?
Benign neoplasms closely resemble the parent tissue – well differentiated
What type of differentiation do malignant neoplasms show?
Malignant neoplasms range from well to poorly differentiated, dependent on how closely they resemble the cell of origin.
What are cells that show no resemblance to any tissue called?
Anaplastic
How do appearance of cells change as differentiation becomes worse?
- Increasing nuclear size
- Increased nuclear to cytoplasmic size
- Increased nuclear staining (hyperchromasia)
- Increased mitotic figures
- Abnormal mitotic figures (Mercedes Benz)
- Variation in size and shape of cells and nuclei (pleomorphism)
What grade represent which type of differentiation?
Grade 1: well differentiated
Grade 2: moderately differentiated
Grade 3: poorly differentiated
Summarise the differences between benign and malignant neoplasms
Benign:
• Expansive Growth
• Grow Locally
• Retained functions of their cells of origin
• Resembles cells/tissues of origin
• Few mitoses
• Normal or mild increase in nuclear to cytoplasmic ratio
• Cells are uniform throughout the tumour
Malignant: • Expansive and invasive • Potential to metastasise • Less likely to retain functions of cells of origin and may sometimes acquire unexpected functions due to derangements in differentiation • Failure to differentiate fully • Many mitoses • High nuclear to cytoplasmic ratio • Cells/nuclei vary in size and shape (pleomorphism)
What are the 2 reasons we get neoplasia?
Non-lethal genetic damage
Accumulated mutations in somatic cells
What 2 factors cause mutations?
initiators and promoters
What are initiators?
mutagenic agents
What are promoters?
cause cell proliferation
Give examples of initiators.
- Chemicals
- Smoking
- Alcohol consumption
- Diet and obesity
- Infectious agents
- HPV
- Radiation
- Inherited mutations
What do initiators and promoters in combination result in?
expanded, monoclonal population of mutant cells
Describe the process of carcinogenesis. Hint : initiation, promotion, progression.
1) Initiation - mutagenic agents/initiators causes mutations in somatic cells. These accumulate.
2) Promotion - promoters cause cell proliferation
3) Progression - A tumour/neoplasm is formed by the clonal expansion of a single precursor cell that has incurred genetic damage. Characterised by the accumulation of yet more mutations.
What is a tumour formed by?
A tumour is formed by the clonal expansion of a single precursor cell that has incurred genetic damage
What is meant by monoclonal and how can this process to neoplasia
A collection of cells is monoclonal if they originated from a single founding cell
Neoplasm then emerges form this group of cells by a process called progression
This is characterised by the accumulation of yet more mutations
Which genes are the targets of cancer to cause mutations
4 classes of normal regulatory genes:
• Growth promoting proto-oncogenes
• Growth inhibiting tumour supressor genes
• Genes that regulate programmed cell death
• Genes involved in dna repair
What are proto-oncogenes and how can they become oncogenes
- Multiple functions but all participate at some level in signalling pathways that drive proliferation
- Mutations that activate these generally cause an excessive increase in one or more normal functions
- Sometimes they impart a completely new function on the affected gene
- “Gain-of-function” mutations
- Oncogenes are created by mutations in proto oncogenes and encode proteins called oncoproteins that have the ability to promote cell growth in the absence of normal growth promoting signals
- They can transform cells despite a normal copy of the same gene
- Oncogenes are dominant over their normal counterparts
What are tumour suppressor genes and how do mutations effect them
- Normal function is to stop cell proliferation
- Generally cause a ‘loss-of-function’
- In most instances both alleles must be damaged for transformation to occur
- Abnormalities in these genes leads to failure of growth inhibition
What are apoptosis regulating genes and how do mutations effect them
May acquire abnormalities that result in less cell death and enhanced survival of cells
How do mutations effect DNA repair genes
- Loss of function mutations
- Contribute indirectly to carcinogenesis
- Impair the ability of the cell to recognise and repair non-lethal genetic damage in other genes
- As a result affected cells acquire mutations at an accelerated rate, a state referred to as a mutator phenotype and is marked by genomic instability
What do the names of benign tumours end in?
-oma
What do the names of malignant tumours end in?
- carcinoma (epithelial neoplasm)
- sarcoma (stromal neoplasm)
What are the 2 different classifications of carcinomas?
- carcinoma in-situ (no invasion through epithelial basement membrane)
- carcinoma invasive (penetrated through basement membrane)
Give examples of benign stratified squamous, transitional and glandular neoplasm
SS=squamous papilloma(any tumour with fingerlike projections) e.g. skin, buccal mucosa
T= transition cell papilloma e.g, bladder mucosa
G= adenoma
cystadenoma e.g. ovary
Give examples of malignant stratified squamous, transitional and glandular neoplasm
SS= squamous cell carcinoma: skin, larynx, oesohpagus, lung, others T= transitional cell carcinoma: bladder, ureters G= adenocarcinoma:stomach, colon, lung, prostrate, breast,pancreas, oesophagus Other = basal cell carcinoma: skin
What do you call benign connective tissue neoplasms?
- smooth muscle: leiomyoma
- fibrous tissue: fibroma
- bone: osteoma
- cartilage: chondroma
- fat: lipoma
- nerve: neuroma
- nerve sheath: neurofibroma
- glial cells: glioma
What do you call malignant connective tissue neoplasms?
- smooth muscle: leiomyosarcoma
- fibrous tissue: fibrosarcoma
- bone: osteosarcoma
- cartilage: chondrosarcoma
- fat: liposarcoma
- glial cells: malignant glioma
What do you call benign and malignant blood vessel neoplasms?
benign: Haemangioma
malignant: Angiosarcoma
What do you call benign and malignant lymph vessel neoplasms?
benign: Lymphangioma
malignant: Lymphangiosarcoma
What do you call benign and malignant smooth muscle neoplasms?
benign: Leiomyoma
malignant: Leiomyosarcoma
What do you call benign and malignant striated muscle neoplasms?
benign: Rhabdomyoma
malignant: Rhabdomyosarcoma
What do you call benign and malignant Stratified squamous epithelium neoplasms?
benign: Squamous cell papilloma
malignant: Squamous cell carcinoma
What do you call benign and malignant Epithelial Lining of Glands or Ducts neoplasms?
benign: Adenoma
malignant: Adenocarcinoma
What do you call benign and malignant Urinary Tract Epithelium neoplasms?
benign: Transitional cell papilloma
malignant: Transitional cell carcinoma
What do you call benign and malignant Blood cells, Lymphoid Tissue, Plasma Cells neoplasms?
malignant:
Leukaemia
Lymphoma
Myeloma
Define leukaemia.
malignant neoplasm of blood forming cells arising in the bone marrow
Define lymphoma.
malignant neoplasms of lymphocytes, mainly affecting lymph nodes
What is myeloma?
malignant neoplasm of plasma cells
Where do germ cell neoplasms arise from?
pluripotent cells, mainly in the testis or ovary
What are blastomas?
occur mainly in children and are formed from immature precursor cells
What is the most common type of cancer?
Carcinomas (90%)
Give examples of germ cell neoplasms
Testis= malignant teratoma and seminoma(a malignant neoplasm) Ovary= benign teratoma = dermoid cyst
