Neoplasms Flashcards
Define tumour
An abnormal swelling
Define neoplasm
An abnormal mass of tissue, the growth of which is uncoordinated with that of normal tissues, and which persists in the same excessive manner after the cessation of the stimulus which evoked the change
Where do tumours result from?
genetic alterations eg mutations in cells, resulting in abnormal growth
cells escape from normal growth regulatory mechanisms
What are the 2 classifications of neoplasms?
Behavioural classification (benign or malignant)
Histogenetic classification (cell of origin)
Describe benign tumours
There are non-invasive and remain localised (don’t spread to other parts of body)
They have a slow growth rate
They share a close histological resemblance to parent tissue
They are typically circumscribed, often surrounded by fibrous capsule
How does an exophytic lesion form?
If they arise on an epithelial or mucosal surface then they grow away from the surface as they can’t invade - thus creating this lesion
What are the problems caused by benign tumours?
Pressure on adjacent tissues
Obstruction to flow of fluid
Production of a hormone
Transformation into malignant neoplasm
Anxiety for patient
Describe malignant tumours
These tumours are invasive and thus capable of spreading directly or by metastasis
They have a relatively rapid growth rate
They have variable histological resemblance to parent tissue
They are poorly circumscribed
tumours on epithelial or mucosal surfaces cause a protrusion in early stages, but eventually invade underlying tissue – ulceration is common
What are the effects of malignant tumours?
Pressure on and secondary destruction of adjacent tissue
Formation of secondary tumours
Infection
Fracture of bones
Neuropathy
Immunosuppression
Haemorrhage, anaemia
Blood loss from ulcerated surfaces
Obstruction of flow
Production of hormone
General weight loss and debility
Anxiety and pain
How do malignant tumours invade other tissues?
- Reduced contact inhibition
- Increased mobility
- Matrix changes
- Enzyme and release
How do malignant tumours spread locally?
- Along perineural spaces (perineural)
- Along sarcolemmal membranes of muscles (sarcolemmal)
- Within the epithelium (pagetoid)
Through which process do malignant tumours spread great distances?
metastasis
Through which 3 sites does metastasis occur?
- Through the bloodstream
- Through the lymphatics
- Across body cavities
How can tumours be classified histogenetically?
- By cell of origin
- Histologically determined
- Degree of histological resemblance to parent tissue allows tumours to be graded
- Histological grade correlates with clinical activity
What is histogenesis?
relates to the specific cell of origin of an individual tumour – this specifies tumour type, and this is incorporated into the name given to the tumour eg squamous cell carcinoma
What are some examples of a benign tumour
Neurofibromas
Lipomas
Haemangiomas
Pleomorphic adenomas (salivary glands)
What are some examples of malignant tumours?
Kaposi’s sarcoma
Squamous cell carcinoma
Malignant melanoma
Adenocarcinomas (salivary glands)
What is differentiation?
the degree to which the tumour resembles histologically its cell or tissue of origin
Why is the degree of differentiation useful?
it correlates strongly with patient survival and their prognosis as it often indicates the most appropriate treatment
we use a grading of 1, 2, 3
What are the names of benign epithelial tumours?
papilloma or adenoma
What do benign connective tissue tumours have to denote cell of origin?
prefix
What is the name of malignant epithelial tumours?
carcinomas
What is the name of malignant connective tissue tumours?
sarcomas
What tumour is the exception of nomenclature that defy accurate classification?
anaplastic tumours
