Negative Pap tests in women with high-grade cervical lesions on follow-up biopsies: Contributing factors and role of human papillomavirus genotyping

Background: Previous studies have indicated that negative Papanicolaou (Pap) tests can precede high-grade cervical lesions (HGCL) on biopsy. This study aims to determine the contributing factors for cytologic discrepancy and the potential role of human papilloma virus (HPV) testing in risk evaluation of women with negative Pap tests. Methods: Of 42,797 Pap tests interpreted as negative for intraepithelial lesion or malignancy (NILM) from March 1, 2013 to December 30, 2014, 426 had available HPV testing and follow-up biopsy. The NILM Pap tests with biopsy-confirmed HGCL were reviewed. Results: Among 426 cytology-negative cases, the biopsies showed benign histology in 243 (57%), low-grade squamous intraepithelial lesion in 157 (37%), HGCL in 22 (5%), and endometrial adenocarcinoma in 4 (1%) cases. The sensitivity/specificity/positive predictive values (PPV) of high-risk HPV (hrHPV) and HPV16/18 tests in predicting HGCL was 91%/45%/8% and 55%/76%/11%, respectively. Upon review of NILM Pap tests with biopsy-confirmed HGCL, the contributing factors to negative cytology included absence of abnormal cells (12/21, 57%) or diagnostic high-grade cells (6/21, 29%), unsatisfactory samples (2/21, 10%), and interpretation variances (1/21, 5%). Interpretation variances in three high-risk lesions (1 HSIL, 2 ASC-H) were influenced by marked obscuring inflammation. Conclusions: Our study demonstrated that 5% of women underwent co-testing with negative Pap tests had HGCL on follow-up biopsy. Absence of diagnostic cells was the leading cause for cytology discrepancy and interpretation variances were influenced by marked obscuring inflammation. HPV testing and genotyping had limited value in risk stratification due to extremely low PPV. Focused rescreening of hrHPV-positive NILM with obscuring factors may help reduce interpretation variances.