Re-evaluation of Negative Cone Biopsy Results with Ki-67 and p16 Immunostaining following Positive Cervical Biopsy

Background: Cervical conization is a standard diagnostic method for precancerous lesions. However, its results could be negative despite an initially positive punch biopsy. The present study aimed to re-evaluate pathological biopsies with Ki-67 and p16 immunostaining to assess the diagnostic accuracy of punch biopsies. Methods: This retrospective study performed in Motahhari Clinic and Shahid Faghihi Hospital, Shiraz, Iran, 88 punch and cone biopsy slides from 2007-2016 were re-evaluated by two pathologists and the results were compared with the original diagnoses. Agreement between the initial diagnoses and re-evaluations and between our pathologists were assessed with the kappa coefficient. Twenty-two negative conization results after positive punch biopsy were re-sectioned and evaluated with Ki-67 and p16 immunostaining. Results: The overall agreement (kappa) between the primary punch diagnoses by the original pathologists and those made in the present study (by the first and second pathologists) before immunohistochemical (IHC) staining was 0.33 and 0.43, respectively. The kappa coefficient between punch biopsy diagnoses by the first and second pathologists before IHC staining was 0.73, while it increased to 1 after IHC staining with Ki-67 and p16. Out of the 22 specimens with the positive punch and negative cone biopsies on initial diagnosis, cervical intraepithelial neoplasia (CIN) was not confirmed in 11 specimens by our pathologists after IHC staining with Ki-67 and p16. These cases were reclassified as transitional metaplasia or acute/chronic cervicitis. Conclusion: Punch biopsy can be misdiagnosed as CIN positive, leading to unnecessary conization. The use of Ki-67 and p16 markers as appropriate ancillary tests are recommended.