p16INK4A Expression in Squamous Cell Carcinomas of the Vagina and the Vulva in Tunisian Women

Background: The role of p16INK4A expression in uterine cervix cancer is well established. In the remainingfemale lower genital tract cancers, the importance of p16INK4A up-regulation is less clear. In our study, we analyzedthe role of p16INK4A expression and HPV infection in carcinomas of the vulva and the vagina in Tunisian women.Materials and
Methods: We conducted a retrospective study of 30 carcinomas including 15 vulvar squamouscell carcinomas (SCCs) and 15 vaginal SCCs. Immunohistochemistry was used to determine p16INK4A expression.HPV detection and typing was by in situ hybridization.
Results: p16INK4A expression was detected in 86.7% ofvaginal SCCs with a strong and diffuse immunostaining in 60% of cases, and also in 73.3% of vulvar SCCswith focal immunoreactivity in 53.3% The association between p16INK4A expression and HPV infection wassignificant in vaginal SCCs (p=0.001) but not vulvar SCCs (p>0.05).
Conclusions: p16INK4A expression could beused as a useful marker for HPV positivity in vaginal SCCs similar to that described in uterine cervix cancers.However, our data support the presence of 2 different mechanisms for p16INK4A expression in HPV-related andHPV-unrelated vulvar carcinomas.