Predictive Role of the p16 Immunostaining Pattern in Atypical Cervical Biopsies with Less Common High Risk HPV Genotypes.

P16 immunostaining is considered a useful surrogate of transcriptionally active high-risk (hr) HPV infection. Only strong and widespread "block-like" immunoreactivity is considered specific, whereas weak/focal p16 positive immunostaining is considered not specific, and follow-up and HPV molecular detection is not indicated. The aim of the study was to evaluate the presence of HPV DNA and Ki67 immunostaining in 40 cervical atypical biopsies (CALs) with mild and focal histological features suggestive of HPV infection-20 cases with weak/focal p16 positive immunoreactivity and 20 cases negative for p16 expression.