High-grade squamous intraepithelial lesion in women aged <30 years has a prevalence pattern resembling low-grade squamous intraepithelial lesion.

Background: Cervical cytology is the cervical cancer screening test for women aged <30 years because of the low specificity of human papillomavirus tests in this age group. The Bethesda System classifies cervical intraepithelial neoplasia grade 2 (CIN 2) and grade 3 (CIN 3) as high-grade intraepithelial lesions (HSIL). In this study, the authors subclassified cytologic HSIL as suggestive of CIN 2 (HSIL-CIN 2) or CIN 3 (HSIL-CIN 3) and evaluated whether there was a correlation between these findings and age for screened and unscreened women.

Methods: The study included 2,002,472 cervical smears collected from women who had at least 1 previous test (screened) and 217,826 previously untested women (unscreened). The laboratory has been using the Bethesda System since 1998 with the subcategorization of HSIL-CIN 2 and HSIL-CIN 3.

Results: For unscreened women, the prevalence of low-grade intraepithelial lesion (LSIL) and HSIL-CIN 2 decreased with age, whereas the prevalence of HSIL-CIN 3 increased. The prevalence of HSIL-CIN 2 was greater than that of HSIL-CIN 3 for women up to age 29 years (prevalence ratio [PR], 4.73; 95% confidence interval [CI], 3.90-5.75) and lower for the groups ages 30 to 49 years (PR, 0.66; 95% CI, 0.50-0.87) and ≥ 50 years (PR, 0.21; 95% CI, 0.12-0.36). For screened women, the prevalence of HSIL-CIN 2 also was greater in the group aged ≤ 29 years (PR, 2.72; 95% CI, 2.49-2.97).

Conclusions: The prevalence pattern of HSIL suggestive of CIN 2 resembled the pattern observed in LSIL and was more prevalent than HSIL suggestive of CIN 3 in younger women. The impact of screening was less evident when HSIL was suggestive of CIN 2. A conservative approach for younger women who have HSIL is important for management guidance.