Diagnosis and grading of cervical intraepithelial neoplasias

Diagnosing and grading of cervical intraepithelial neoplasias (CIN) are part of the routine practice of pathologists. However, discriminating between reactive changes and CIN1 and determining the different degrees of CIN may be challenging. Aim of this study was the evaluation of the proliferation markers Ki-67 and Mcm2 as well as p16 for their potential to aid in the assessment of CIN. 297 samples of normal epithelium, CIN1, CIN2, and CIN3 were assessed for expression of the above mentioned markers using tissue microarrays. There was an increase in the expression of Ki67 and Mcm2 from normal epithelium, CIN1, CIN2 to CIN3 (p < 0.001 for both markers). Ki-67 was the most useful marker in differentiating between normal epithelium and CIN1. The number of p16-positive cases was 7% in CIN1, 46% in CIN2 and 86% in CIN3. There were no p16-positive cases in the group with normal epithelium. In order to grade CIN1 vs. CIN2 a combination of Ki-67 and p16 was helpful. Cases with a proliferation rate of < 25% assessed with Ki-67 were most likely CIN1 (sensitivity 91.7%, specificity: 54.3%, positive predictive value: 73.3%, negative predictive value 82.6%). P16 was the most helpful marker in distinguishing between CIN2 and CIN 3 as p16 negative cases were more likely to belong into the CIN2 category. In summary, the histopathological assessment of cervical biopsies is based on H&E-stained slides. However, Ki-67 and p16 can be helpful in diagnosing and grading cervical intraepithelial neoplasia.