Disorder of growth, differentiation and tumour Flashcards
What is growth
Growth is the process of increase in size resulting from the synthesis of specific tissue components
What is differentiation
- A process whereby a cell develops an overt specialised function or morphology which distinguishes it from its parent cells
What is Tumour differentiation
- refers to the extent to which neoplastic cells resemble comparable normal cells, both morphologically and functionally
What is Anaplasia
- Lack of differentiation is called anaplasia
What is Anaplasia a hallmark for
A hallmark of malignant transformation
What does Anaplasia mean
- Means “to form backward” implying a reversion from a high level of differentiation to a lower level
Name the morphological changes of anaplasia
- Pleomorphism
- Abundance of DNA
- Mitoses
- Loss of polarity
- Other changes: Formation of tumour giant cells
What is Pleomorphism like in morphological changes of anaplasia
- Variation in size and shape
What is Abundance of DNA like in morphological changes of anaplasia
- Nuclei are disproportionately large for the cell
What is Mitoses like in morphological changes of anaplasia
- Mitosis does not necessarily indicate that a tumour is malignant or that the tissue is neoplastic
What is Loss of polarity like in morphological changes of anaplasia
- The orientation of cells is markedly disturbed
What is Neoplasia?
- An abnormal mass of tissue, the growth of which exceeds and is uncoordinated with that of the normal tissues and persists in the same excessive manner after cessation of the stimuli which evoked the change
What does Neoplasia mean
- Means the process of “new growth” and new growth is called a neoplasm
What are the different types of tumours (neoplasm)
- Benign or Malignant
What is malignant tumours also known as
- cancer
What is the Behavioural classification of tumours
- Benign or malignant
What is the Histogenetic classification of tumours
- cell of origin
What is the nomenclature of tumours
- All have the suffix ‘-oma’
- Benign epithelial tumours are either papilloma’s or adenomas
- Benign connective tissue tumours have a prefix denoting the cell of origin
- Malignant epithelial tumours are carcinomas
- Malignant connective tissue tumours are sarcomas
What are the characteristics of Benign tumours
- Non-invasive and remain localised
- Slow growth rate
- Close histological resemblance to parent tissue
- A fibrous capsule to separate tumour from the host tissue, readily palpable and early moveable surgically
What are the characteristics of Malignant tumours
- Invasive and capable of spreading directly or by metastasis
- Relatively rapid growth rate
- Variable histological resemblance to the parent tissue
Compare the growth rate of Benign and Malignant tumours
Benign - slow
Malignant - relatively rapid
Compare the Mitotic activity of Benign and Malignant tumours
Benign - Low
Malignant - High
Compare the Histological feature (to original tissue) of Benign and Malignant tumours
Benign - Good
Malignant - Often poor
Compare the Invasion of Benign and Malignant tumours
Benign - No
Malignant - Yes
Compare the Metastases of Benign and Malignant tumours
Benign - Never
Malignant - Frequent
Compare the Border of Benign and Malignant tumours
Benign - circumscribed or encapsulated
Malignant - poorly defined or irregular
Compare Necrosis of Benign and Malignant tumours
Benign - Rare
Malignant - Common
What is Metaplasia
- A reversible change in which one adult cell type (epithelial or mesenchymal) is replaced by another adult cell type
- May represent an adaptive substitution of cells that are sensitive to stress by cell types better able to withstand the adverse environment
What is Metaplasia often association with
- Often in association with tissue damage, repair and regeneration
What happens if influence that are predispose to metaplasia is persistent
- May initiate malignant transformation in metaplastic epithelium
What does the term Dysplasia mean
- A term that literally means disordered growth
Where is Dysplasia encountered
- Is encountered principally in metaplastic epithelia
Dysplastic lesions are often what?
pre-neoplastic
What is the architecture like for Dysplasia
- The architecture of the tissue may be disordered
Does dysplasia progress to cancer
- Dysplasia does not necessarily progress to cancer
What is the characteristics of Dysplasia
- Loss in the uniformity - of the individual cells and in their architectural orientation
- Exhibit considerable pleomorphism and often contain hyperchromatic nuclei that are abnormally large for the size of the cell
- Mitotic figures: abundant and appear in abnormal locations within the epithelium (not confined to the basal layers)
What is Metastasis
- Metastases are tumour implants discontinuous with the primary tumour (only for malignant tumours)
How does metastasis mark a tumour as malignant
- Because benign neoplasia do not metastasize
Metastatic spread strongly reducing the possibility of what?
- a cure
- Methods to block metastases would be of great benefit to patients
What pathways of spread does Metastasis go
Pathways of spread:
- DIRECT SEEDING of body cavities or surfaces: pleural, pericardial and peritoneal cavities
- LYMPHATIC SPREAD: secondary tumours in the regional lymph nodes
- HAEMATOGENOUS SPREAD (by the blood stream): secondary tumours in organs perfused by blood from a tumour
- IMPLANTATION (after operation) : Rare
What is carcinogenesis
- Non lethal genetic damage is the basis carcinogenesis
- Carcinogenesis is a multi-step process at both the phenotypic and genetic levels
How is a tumour formed by carcinogenesis
- A tumour is formed by the clonal expansion of a single precursor cell that incurred genetic damage
What are the 4 classes of regulatory genes that are the principal targets of genetic damage
- The growth promoting oncogenes
- The growth inhibiting tumour suppressor genes
- Genes that regulate and programmed cell death (apoptosis)
- Genes involved in DNA repair
