Comparison of human papillomavirus distribution in cytologic subgroups of low-grade squamous intraepithelial lesion

Low-grade squamous intraepithelial lesion (LSIL) subsumes the formerly delineated cytologic categories of human papillomavirus (HPV)-associated cell changes (koilocytotic atypia) and low-grade dysplasia/cervical intraepithelial neoplasia (CIN) Grade 1 (CIN1). In this study, the objective was to determine whether these 2 morphologic subcategories are characterized by differences in risk for CIN3 and/or HPV type distribution.

Within the Atypical Squamous Cells of Undetermined Significance/Low-Grade Squamous Intraepithelial Lesion Triage Study, all cytologic interpretations of HPV cellular changes and CIN1 rendered by any of the pathology reviewers (community laboratory, clinical center, or Pathology Quality-Control Group) on referral Papanicolaou (Pap) tests or enrollment ThinPrep Pap tests were included for analysis. HPV testing was performed by Hybrid Capture 2 (HC2) and by polymerase chain reaction based reverse-line blot analysis for 27 HPV types. The absolute risks of cumulative detection of CIN3 or cancer (CIN3 +) and CIN2 or worse (CIN2 +) over 2 years of follow-up were calculated for the various cytologic interpretations.

For each review group and cytology preparation, most LSIL interpretations (from approximately 2 of 3 interpretations to 3 of 4 interpretations) were subcategorized as CIN1 rather than HPV cellular changes. HPV type 16 (HPV-16) was the most common HPV type and was identified in 21% to 24% of CIN1 and in 14% to 18% of HPV cellular changes. Nononcogenic types were identified alone in from 9% to 11% of CIN1 compared with 17% to 20% of HPV cellular change. The absolute risks of CIN1 and HPV cellular changes for cumulatively detected CIN3 + ranged from 12% to 16% for CIN1 and from 6% to 9% for HPV cellular changes.

Both cytologic subcategories of LSIL were associated predominantly with oncogenic HPV types; however, the proportion of nononcogenic HPV types was lower and the absolute risks for CIN3 + were higher for CIN1 compared with HPV cellular changes. The concordance in subcategorizing LSIL was low, and the authors concluded that the diagnostic distinction is of limited clinical utility for individual patient management.