p16 expression in relation to human papillomavirus in anogenital lesions

Recent studies have revealed that cervical cancers associated with high-risk human papillomavirus (HPV) showed overexpression of the p16 protein, a cyclin-dependent kinase inhibitor. The expression of this cell cycle regulator in lesions of the anogenital region in association with HPV physical status (episomal or integrated) has not been studied at the present time. In this report, immunohistochemical analysis of p16 and HPV detection by in situ hybridization were performed on I 10 formalin-fixed and paraffin-embedded samples of anogenital lesions. The results showed strong diffuse p16 staining in all integrated high-risk HPV-positive lesions, whereas most episomal HPV-positive lesions or HPV-negative lesions showed no p16 immunostaining. However, there were a few HPV-negative lesions or lesions with episomal HPV harboring p 16 overexpression. On the other hand, some lesions were p 16 negative while showing the presence of high-risk HPV in its episomal form. In conclusion, screening for p 16 overexpression in cutaneomucous lesions of the anogenital region allowed good discrimination between HPV-integrated lesions and lesions harboring episomal HPV or no HPV. But p 16 overexpression was not always predictive of the presence of high-risk HPV; moreover, absence of p 16 immunostaining observed in some high-risk HPV lesions suggested that limiting the screening to p16 would exclude some patients harboring high-risk HPV from any follow-up. (c) 2006 Elsevier Inc. All rights reserved.