Role of p16INK4A/Ki-67 dual immunostaining on cell blocks in detecting high-grade cervical intraepithelial lesions

Background: P16/Ki-67 dual immunostaining has been confirmed as a sensitive and specific test for human papillomavirus positive women. In the present study, we evaluated cell blocks (CBs) with p16^INK4A/Ki-67 biomarkers to detect high-grade cervical intraepithelial neoplasia (CIN). Materials and Methods: Samples for CB preparation were taken from females with abnormal Pap smears, who also underwent colposcopic guided biopsies, P16^INK4A and Ki-67 staining were performed on CBs and tissue biopsies, histopathology with p16^INK4A expression was considered the gold standard. Sixty-five specimens were included in the study. Results: The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy (AC) of CB + p16^INK4A/Ki-67 in detecting CIN2 when considering only cytology specimens with the low-grade squamous intraepithelial lesion (LSIL) were 86.67%, 100%, 66.67%, 89.66%, and 82.93%, respectively. The sensitivity, specificity, PPV, NPV, and AC of CB + p16^INK4A/Ki-67 in detecting CIN2 when considering only cytology specimens with atypical squamous cells of uncertain significance/LSIL were 75%, 85%, 60%, 91.89%, 82.69%, respectively. Rates of positive staining for p16 ^INK4A/ki-67 were enhanced according to increased pathologic grade and differed statistically between CIN1 and CIN2 as well as squamous cell carcinoma. Conclusion: CB preparation technique with p16^INK4A and Ki-67 immunostainings have improved the diagnostic AC of Pap smear in detecting high-grade CIN.