Combined detection of p16INK4a and IMP3 increase the concordance rate between cervical cytologic and histologic diagnosis

Currently, there are discrepancies in the interpretation between cervical liquid-based cytology (LBC) and histologic diagnoses. The aim of our study was to evaluate the utility of p16^INK4a (p16) and IMP3 staining of LBC specimens to increase the concordance rate. A total of 98 cell blocks with biopsy results, including 37 low-grade squamous intraepithelial lesions (LSIL), 36 high-grade squamous intraepithelial lesions (HSIL), and 25 squamous cell carcinomas (SCC), were selected for the immunocytochemical analysis of p16 and IMP3. The LBC diagnoses corresponded with histological diagnoses for 59.5% (22/37), 63.9% (23/36), and 88.0% (22/25) of LSIL, HSIL, and SCC lesions, respectively. We found a high frequency of p16 positivity in HSIL (72.2%) and SCC (100%), but not LSIL (29.7%). IMP3 was frequently expressed in SCC (84.0%), but rarely in LSIL (8.1%) and HSIL (25.0%). Cervical intraepithelial neoplasia 1 (CIN1) was negative for both p16 and IMP3, CIN2/3 tended to be positive for p16 and negative for IMP3, and SCC was positive for both p16 and IMP3. The combination of p16 and IMP3 immunostaining had a higher sensitivity and specificity for detecting CIN1 and CIN2/3 than cytology. For detecting SCC, p16/IMP3 had a higher sensitivity than cytology, but a lower specificity. IMP3 is a useful diagnostic immunomarker that can be used to identify SCC and the combination of p16/IMP3 expression was found to improve the discrepant results between cytologic and histologic diagnoses.