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 remaining female lower genital tract cancers, the importance of p16INK4A up-regulation is less clear. In our study, we analyzed the 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 squamous cell 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% of vaginal SCCs with a strong and diffuse immunostaining in 60% of cases, and also in 73.3% of vulvar SCCs with focal immunoreactivity in 53.3% The association between p16INK4A expression and HPV infection was significant in vaginal SCCs (p=0.001) but not vulvar SCCs (p>0.05). CONCLUSIONS p16INK4A expression could be used 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 and HPV-unrelated vulvar carcinomas.