Evaluation of p16 immunostaining to predict high‐grade cervical intraepithelial neoplasia in women with Pap results of atypical squamous cells of undetermined significance

p16 immunostaining has been examined to detect high‐grade cervical intraepithelial neoplasia grade (CIN2+) in Pap cytology specimens. However, the utility of p16 in predicting CIN2+ in Pap specimens with atypical squamous cells of undetermined significance (ASC‐US) or atypical squamous cells, cannot exclude high‐grade squamous intraepithelial neoplasm (ASC‐H), is controversial. In this study, we evaluated the utility of p16 immunostaining for predicting CIN2+ in 78 Pap specimens with ASC‐US/ASC‐H and compared the results in high‐risk HPV DNA and the follow‐up biopsies. p16 immunostaining was positive in 47% (37/78) of the Pap specimens. Of the 13 Pap specimens with follow‐up biopsy results of CIN2+, 7 (54%) were positive for p16. p16 positivity in the Pap specimens was not significantly associated with a CIN2+ biopsy result (P = 0.76). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of p16 immunostaining for predicting CIN2+ were 54%, 52%, 19%, and 85%, respectively. High‐risk HPV DNA was detected in 40% (31/78) of the Pap specimens. The sensitivity, specificity, PPV, and NPV of HPV DNA for predicting CIN2+ were 100%, 72%, 42%, and 100%, respectively. High‐risk HPV genotypes were detected in six p16‐negative specimens with follow‐up biopsy results of CIN2+. Our findings suggest that the utility of p16 immunostaining for predicting CIN2+ in Pap specimens with ASC‐US/ASC‐H is limited. Scant abnormal cells in Pap specimens with ASC‐US/ASC‐H may have contributed to the low p16 sensitivity. Diagn. Cytopathol., 2011. © 2010 Wiley‐Liss, Inc.