[Immunohistochemistry of p16INK4a in biopsies and cervicovaginal smears, and its correlation with HPV detected by PCR].

Recent studies suggest that p16 overexpression determined by immunohistochemistry would be a specific marker for neoplastic and dysplastic squamous cells associated with high-risk HPV. The purpose of this study was to assess the correlation between cyto-histological findings, p16 expression and HPV subtype. A total of 99 biopsies were selected, 4 endocervical curettages and 95 uterine cervix biopsies, as well as 30 cervicovaginal smears from other 30 patients. The samples were divided according to the morphological diagnosis. Paraffin-embedded sections and cervicovaginal smears were immunostained using the CINtec p16INK4a Cytology Kit (DAKO). HPV was analyzed by PCR in 25 of the 99 biopsies with low-grade squamous intraepithelial lesion. Among those patients with neither HPV nor dysplasia, 1 of 35 (2.9%) biopsies and 1 of 11 (9%) smears were positive for p16. Sixteen of 25 (64%) biopsies and 6 of 10 (60%) smears of the low-grade lesion cases, and 38 of 39 (97.4%) biopsies and 8 of 9 (89%) smears of the high-grade lesion and squamous carcinoma were positive for p16. All cases of HPV-6/11 were negative or focally positive for p16. Most cases of HPV-18 or other subtypes were diffusely positive. Our results indicate that p16 expression is highly correlated with cyto-histological diagnosis, and is associated with diffuse staining and high-risk HPV. This technique provides greater objectivity in doubtful cases, and helps select patients at risk of disease progression at an acceptable cost when used in large populations.