Introduction to benign and malignant disease Flashcards
Which cells are not capable of replicating?
Terminally differentiated cells (e.g myocytes - muscle cells)
Quiescent cells
In a state or period of inactivity/dormancy
What cells are normally quiescent in liver/kidney?
Differentiated cells
Describe the epithelia of the oral cavity, gut, skin.
The mature cells are terminally differentiated, short-lived and incapable of replicating but may be replaced by new cells arising from stem cells.
Hypertrophy
An increase in cell size (physiological or pathological) - seen in muscle skeletal and cardiac.
Hyperplasia
An increase in cell number (physiological or pathological) - seen in hormonally sensitive organs (endometrium, breast, thyroid etc).
Can be seen through enlargement of gingival tissues, hyperplastic responses within epithelium and underlying connective tissue.
Atrophy
Reduction in cell size by loss of cell substance.
Many causes (physiological (thyroglossal duct) and pathological) - ageing, lack of use/stimulation, mechanical, functional.
Hypoplasia
Reduced size of an organ that never fully developed to normal size.
A developmental defect.
The only change that is irreversible.
Metaplasia
The reversible change in which one adult cell type is replaced by another adult cell type. Can be part of an adaptive response to stress. Reprogramming of stem cells. Examples include Barrett’s oesophagus, bronchus, salivary ducts (sialometaplasia).
Can also affect mesenchymal tissues but not in itself a neoplastic disorder.
Dysplasia
A term used to describe the presence of abnormal cells within a tissue or organ.
Congenital hip dysplasia, fibrous dysplasia.
Epithelial dysplasia (intraepithelial neoplasia, premalignant change).
Neoplasia
An abnormal mass of tissue that forms when cells grow and divide more than they should or do not die when they should.
Different degrees of dysplasia
Mild, moderate and severe (carcinoma in situ).
The more severe, the more risk of progressing to invasive malignancy.
In tissue showing dysplasia, at what point does classification go from non-invasive cells to invasive cancer cells?
Not invasive when the abnormal cells remain within the epithelium.
Once the abnormal cells breach the basement membrane of the epithelium invade into the underlying and surrounding tissue that they can be referred to as invasive cancer.
Moderate dysplasia
Severe dysplasia
Neoplasia
New growth
Abnormal mass of tissue, growth of which exceeds what is normal.
What causes neoplasia?
Aberration of the normal mechanisms that control cell number (cell production/cell loss).
What can be said about the lineage of most tumours?
Most tumours are monoclonal i.e all the cells in a tumour appear to arise from one parent cell which has undergone a genetic change. This is then passed on to all the progeny.
Two main ways to define tumours
By their 1. Behaviour OR 2. histogenesis
Types of tumour behaviours
Benign OR malignant
Benign tumours
- Growth pattern: stay localised, well-circumscribed, often encapsulated.
- Growth rate: slower
- Clinical effects: local pressure effects; hormone secretions
- Treatment: local excision
What is this?
Pleomorphic adenoma; the most common type of benign salivary gland adenoma. Usually found in parotid gland.
Histology of a pleomorphic adenoma: comprises of epithelial and myoepithelial cells set in a loose stroma
What is shown here?
Oral squamous cell carcinoma
Describe the image
Oral squamous-cell carcinoma: shows considerable variation and pleomorphism of the nuclei and also abnormal cross form mitotic figures seen in the centre of the image
What’s in this picture?
Left: Benign squamous cell papilloma
Right: Malignant melanoma
Why is tumour grade an important consideration?
Involves histological assessment to see how differentiated the tumour cells are. Well differentiated tumours tend to have better prognosis.
