The Pathology of Cervical Dysplasia and Malignancy Flashcards
What are the histological gradings of precancerous cervical squamous lesions?
HPV, CIN1-3
What are the cytological gradings of precancerous cervical squamous lesions?
low grade (encompassses HPV and CIN1) or high grade (encompasses CIN 2 and CIN 3)
What type of virus is HPV?
a double stranded DNA virus
Where does HPV infect?
squamous epithelium - at the mouth, genitals and skin (most commonly hands)
How many different types of HPV are there?
130
What is meant by high risk and low risk HPV?
their oncogenic potential
Where is there the highest incidence of HPV?
Africa, Asia and Latin America
What percentage of cervical cancers are attributable to HPV?
100%
Which HPV types account for the majority of cervical cancers?
HPV-16 and HPV-18
Which age group has the highest prevalence of HPV?
20-24
What are the late genes of the HPV DNA responsible for?
the capsid
What are the early genes of the HPV DNA responsible for?
replication, proliferation and viral release
How does HPV infect?
there has to be pre-existing damage so that HPV can gain access to the basement membrane or basal keratinocytes - as capsid gains contact it can enter cells
How does HPV propagate throughout cells?
with cell replication
How does HPV reinfect?
as the keratinocytes are sloughed the HPV is released so its able to reinfect
What is the structure of the DNA within the infected cells?
either episomal or integrated into the host DNA
What is the role of the HPV E2 gene?
supresses transcription of HPV E6 and E7 genes
What is the role of HPV E6 and E7 genes?
E6 binds to p53 (a tumour supressor gene) and deactivates it, E7 binds to Rb and deactivates it - the result of their expression is squamous cell carcinoma
When are E6 and E7 expressed?
when the HPV integrates with the host DNA at a breakpoint in E2
What is the difference between low risk and high risk HPV?
low risk is more likely to become latent and regress where as high risk is more likely to cause SCC
What is the transformation zone?
the function between the ectocervix and endocervix - it is the site that is most susceptible to HPV
What is a cervical condyloma?
a genital wart - there is no dysplasia but the squamous epithelium is thickened and there are koilocytes
What are koilocytes?
squamous epithelial cells with nuclear enlargement, irregularity of the nuclear membrane, hyperchromasia and nuclear halo
What is a flat condyloma?
a flat cervical lesion - contains koilocytes but isnt papillomatous
