Oral carcinogenesis and oral epithelial dysplasia Flashcards
What is a tumour?
abnormal, uncoordinate tissue growth which persists after initiating stimulus is gone
What is cancer?
What affect can cancer have on surrounding structures and further away?
local tissue invasion and destruction
can also metastasise and reach far away tissues and organs
How does cancer get its name?
cancer = crab
crab like projections of abnormal epithelium into subcutaneous connective tissue
What causes cancer
carcinogenic substances or spontaneous mutation (possibly genetic factors)
What are the 1st and 2nd most common oral cancer?
SCC (90-95%)
minor salivary gland carcinoma
Name some primary (5) and secondary (2) oral tumours.
primary: OSSC minor salivary gland carcinomas lymphoma malignant melanoma sarcoma
secondary:
metastatic adenocarcinomas
Principal signs and symptoms that could help identify oral cancer (pneumonic)
Oral ulceration, non healing for >2weeks
Red or white patches
Abnormal growths/swellings
Loss of tongue mobility
Cauliflower like growths Abnormal localised tooth mobility Non-healing sockets Colour changes to mucosa (brown/blue) Erosions in mucosa Reduced or altered sensation
Mechanisms and markers of oral carcinogenesis
tumour suppressor genes (p53) oncogenes loss of cell adhesion viruses immortalisation angioneogenesis
cell cycle disruption genetic abnormalities (DNA aneuploidy)
Explain the changes and types of cells from normal to epithelial dysplasia to invasive SCC
in normal: (2)
growth promoting and inhibiting factors IN BALANCE
-> cells: oral keratinocytes and stem cells
dysplasia: (5)
- some factor (carcinogen, spontaneous) over-ride normal control mechanisms and cause stem cells to be overactive
- keratinocyte stem cells change to become tumour initiating stem cells
- there is dysregulated cell proliferation (causes unrestricted growth)
- > phase of pre/potential malginancy, process can be halted
invasive SCC (4)
- immortalisation of cells
- neovascularisation
- cell migration
- local invasion and then metastasis
What does epidermal proliferative unit consist of?
stem cells
amplifying cells
non-proliferative supra- basal cells
What is dysplasia?
a spectrum of tissue DYSMATURATION and DISORGANISATION
associated with increased risk of malignant transformation
What two types of changes is the pathologist going to look for?
cytology (changes in cell)
tissue architecture
NAME histological changes in SCC
pleomorphisms drop shaped rete ridges keratin pearls in rete ridges dyskeratinisation loss of polarity of basal cells
WHO grading of dysplasia
mild - architectural changes limited to lower 1/3 of epithelium accompanied by atypical cytology
moderate - limited to middle 1/3, possibly upgrade if high atypia
severe - extending above 2/3s of epithelium
carcinoma in situ - FULL or almost full thickness architectural abnormalities accompanied by high degree of cytological atypia but not invaded through basement membrane