Papanicolaou Tests With Mixed High-Grade and Low-Grade Squamous Intraepithelial Lesion Features: Distinct Performance in the College of American Pathologists Interlaboratory Comparison Program in Cervicovaginal Cytopathology

Performance of specific morphologic features in distinguishing low-grade squamous intraepithelial lesions from high-grade squamous intraepithelial lesions in borderline cases: a College of American Pathologists Cytopathology Committee multiobserver study

INTRODUCTION

Distinguishing between low-grade squamous intraepithelial lesions (LSIL) and high-grade squamous intraepithelial lesions (HSIL) can be difficult on certain Papanicolaou (Pap) tests, hindering interobserver concordance. We investigated the variables influencing the interpretation of LSIL versus HSIL in Pap test slides rejected from the College of American Pathologists PAP education program.

MATERIALS AND METHODS

Eleven cytologists, who were unaware of the reference interpretation, examined 21 Pap slides (11 submitted as LSIL and 10 as HSIL) rejected from the PAP education program and recorded the number of LSIL cells, HSIL cells, keratinized dysplastic cells, LSIL clusters with mixed HSIL cells, atypical squamous metaplasia, atypical glandular cells, the presence of inflammation or infectious organisms, and the overall interpretation (LSIL or HSIL). We evaluated the significance of these 11 variables using a nonlinear mixed model analysis.

RESULTS

LSIL had greater concordance (92 of 121 responses; 76.0% concordance) than HSIL (68 of 110 responses; 61.8% concordance; P < 0.001). The only predictors of misclassified cases were the number of atypical squamous metaplastic cells and the number of HSIL cells (P < 0.001). The more of these cells identified, the more likely the reviewers were to classify the slide as HSIL. The reproducibility of the diagnosis was fair (Gwet's agreement coefficient, 0.33).

CONCLUSIONS

Interobserver reproducibility is a challenge for a subset of cases with features intermediate between LSIL and HSIL. Atypical squamous metaplasia and dysplastic nuclei with a nuclear/cytoplasmic ratio greater than one half of the cell volume (HSIL) present on a Pap test influenced the likelihood that a reviewer would interpret the case as HSIL rather than LSIL.

Moving forward-the 2019 ASCCP Risk-Based Management Consensus Guidelines for Abnormal Cervical Cancer Screening Tests and Cancer Precursors and beyond: implications and suggestions for laboratories

The 2019 ASCCP Risk Based Management Consensus Guidelines for prevention of cervical cancer promote clinical management recommendations aligned with our increased understanding of HPV biology and cervical carcinogenesis. They employ HPV-based testing as the basis for risk estimation, allow for personalized risk-based management by incorporating knowledge of current results with prior results, and streamline incorporation of new test methods as they are validated. They continue to support the principles of "equal management for equal risk" and "balancing harms and benefits" adopted in the 2012 version of the guidelines. These updated guidelines will be able to adjust for decreasing CIN3+ risks as more patients who received HPV vaccination reach screening age. Pathology organizations were closely involved in the development of these guidelines. Herein the pathologists who served as representatives to the 2019 ASCCP guidelines steering committee and workgroups, summarize the changes that are relevant to laboratories, pathologists, and cytotechnologists. Prior relevant screening and reporting recommendations that have not been widely and/or inconsistently adopted by laboratories are also discussed and considerations for modification of laboratory practices offered.

Human papillomavirus testing for triage of women with low-grade squamous intraepithelial lesions

Low-grade squamous intraepithelial lesion (LSIL) is a common cytologic finding in cervical screening, yet only about 10-20% have significant histologic abnormalities and these are almost always positive for high-risk human papillomavirus (hrHPV). This analysis aims to clarify the role of hrHPV DNA testing in the triage of women with LSIL cytology. In the ATHENA screening trial, we examined 1,084 cases of LSIL, of which 925 had an evaluable biopsy, to determine the extent to which hrHPV testing can identify those patients who have precursor lesions in need of immediate clinical referral and those who have changes more likely to regress spontaneously. Overall, 71.2% of LSIL cases were hrHPV positive, but the prevalence was age dependent, with only 56.1% in women ≥ 40 years. Among women with LSIL, 11.6% (107/925) had a cervical intraepithelial neoplasia grade 2 or worse (CIN2+) histologic diagnosis and, of these, only nine were hrHPV negative. For CIN3+, 91.7% (44/48) of women with LSIL were hrHPV positive. The negative predictive value of hrHPV testing for CIN3+ in LSIL was 100% for women aged ≥ 40 years. Women who were HPV16 positive had a higher positive predictive value for CIN2+ (25.4%) than those who were positive for 12 other pooled hrHPV types (11.5%). Testing for hrHPV in women with LSIL is effective in identifying high-grade cervical lesions, thereby avoiding unnecessary referrals to colposcopy and potential over-treatment of non-progressive lesions, especially for women aged ≥ 40 years.