Histology Flashcards
What type of epithelium is the palate?
Keratinised
What type of epithelium is the cheek?
Non-keratinised
What is acanthosis?
Hyperplasia of stratum spinosum
What are elongated rete ridges?
Hyperplasia of basal cells
What is keratosis in a non-keratinised site?
Parakeratosis
What is atrophy?
Reduction in viable layers
What is erosion?
Partial thickness loss
What is ulceration?
Full thickness loss with fibrin on surface
What is dysplasia?
Disordered maturation (growth) in a tissue
Atypia- changes in cells
Changes in appearance of cells, function, arrangement to other cells
What is an epulide?
Soft tissue swelling on the gingiva only
Reaction to chronic inflammation/chronic trauma
Can reoccur after removal if stimulus persists
What is a fibrous overgrowth?
Localised gingival hyperplasia
Can be:
–fibrous epulis
–vascular epulis (pyogenic granuloma)
What causes giant cell lesions?
Unphagocytosable materials
–local chronic irritation
–infective agents e.g. TB bacillus
–hormonal stimulation of cells- osteoclasts
Autoimmune- Sarcoidosis
What drugs can induce fibrous overgrowths?
Anti-hypertensives
–calcium channel blockers
Anti-epileptics
–phenytoin
Immunosuppressants
–cyclosporin
What is a potentially malignant condition?
Generalised state with increased cancer risk
What are some potentially malignant conditions related to the oral cavity?
Lichen planus
Oral submucous fibrosis
Iron deficiency
Tertiary syphilis
What is chronic hyperplastic candidosis?
Appears at the commissures of the lips
Dysplasia may be present
Common in smokers
What is the pathology of chronic hyperplastic candidosis?
Special stain needed to demonstrate candida albicans hyphae clearly
PAS (periodic schiff stain)
What is the treatment for chronic hyperplastic candidosis?
Systemic antifungals (fluconazole- 1xdaily for 14 days
Biopsy
Stopping smoking
Observe
How many more x likely is leukoplakia to form cancer than clinically normal mucosa?
50 to 100 times
What are the predictors of malignancy in leukoplakia?
Age
Gender
Idiopathic
Site
–buccal mucosa- low risk
–floor of mouth, tongue- high risk
Clinical appearance
–homogenous
–non-homogenous; verrucous, ulcerated
What type of leukoplakia has the highest malignant transformation?
Proliferative verrucous leukoplakia
What are the molecular markers in oral epithelial dysplasia?
Signalling pathways- EGFR
Cell cycle- K/67, p53, pRB
Immortalisation- telomerase
Apoptosis- p53, p21
Angiogenesis- VEGF
COX-1 & 2 enzymes
Proliferation and differentiation markers
Viruses- HPV+ and HPV-
What is the epithelium of basal hyperplasia?
Increased basal cell numbers
Architecture
–regular stratification
–basal compartment is larger
No cellular atypia
What is carcinoma-in-situ?
Theoretic concept
Malignant but not invasive
Abnormal architecture
–full thickness (or almost full) of viable cell layers
Pronounced cytological atypia
–mitotic abnormalities frequent
What are the 2 main factors of carcinogenesis?
Genetic
Environmental (carcinogens)
What is the molecular basis of cancer?
Damage
Altered gene expression
Altered cell function
What is involved in oral cancer genetics?
Oncogenes- have normal roles within the cells, differing oncogenes activated
Tumour suppressor genes- suppress the growth of cells
P53 mutation or inactivation
Genes that regulate apoptosis
Genes involved in DNA repair
Viral component- HPB
What can changes to genes include?
Changes to chromosomes (translocations, amplifications)
Genes (mutations, deletion, amplifications)
Epigenetic changes (chemical changes in DNA)
What are the hallmarks of cancer?
Self-sufficiency in growth signals
Insensitivity to anti-growth signals
Evading apoptosis
Sustained angiogenesis
Tissue invasion & metastasis
Limitless replicative potential
How does oral cancer spread?
Local extension of disease
–varies according to site
–mucosal extension
–muscle (tongue etc)
–bone
–nerve
Lymphatic spread
Haematogenous spread
What is perineural spread?
Perineural spread involves small nerves at advancing edges which predicts nodal spread
Extensive spread related to inferior alveolar nerve may give recurrence
