P16 ink4a and HPV L1 immunohistochemistry is helpful for estimating the behavior of low-grade dysplastic lesions of the cervix uteri

As only a minority of low-grade dysplastic lesions of the cervix uteri will eventually progress to carcinoma, predicting the behavior of these lesions could be of high value in clinical practice. The aim of the study was to evaluate p16 ink4a and L1 as immunohistochemical markers of the biologic potentiality of low-grade dysplasia of the uterine cervix. The study included 38 conization specimens with coexisting cervical intraepithelial neoplasia grade 1 (CIN1) and 3 (CIN3) (group A) and 28 punch biopsies from women with CIN1 and proven spontaneous regression in the follow-up (group B). In group A, all CIN3 were p16 ink4a positive (p16+) and L1 negative (L1-). The CIN1 of this group were p16+L1- and p16+L1+ in 68.42% and 31.57%, respectively. No other expression pattern was found in this group. In group B, the p16+L1-, p16+L1+, p16-L1+, and p16-L1- patterns were found in 3.57%, 25%, 14.29%, and 57.14%, respectively. Overall, 96.29% p16+L1- CIN1 were found in group A, whereas all the p16-L1+ and p16-L1- CIN1 were found in group B. A significant difference between staining pattern distributions of group A and B was observed (P<0.0001). The results of the study show that p16 ink4a and L1 immunohistochemistry can be helpful for estimating the biologic potentiality of low-grade squamous cervical lesions. Particularly in cases in which the grade of the lesion is morphologically difficult to assess, the p16/L1 expression pattern could be useful for planning the clinical management of these women.