Risks for Incident Human Papillomavirus Infection and Low-Grade Squamous Intraepithelial Lesion Development in Young Females

Abstract

Low-grade squamous intraepithelial lesions (LSILs) are relatively common manifestations of cervical human papillomavirus (HPV) infections. Most pathologists agree that LSIL is a cellular response to HPV infection^1,2 resulting from the expression of specific viral proteins that interact with the host cytoskeletal structures and induce cell proliferation.^3-5 Some researchers suggest that all HPV infections result in pathologic changes of LSIL at some point in the natural history of infection; however, the discrepancy between rates of infection with HPV and development of LSIL is quite striking, even in adolescent and young women in whom the prevalence of both is high. Rates of HPV infection in sexually active young females have been consistently reported to range from 19% to 46%; these are significantly higher than reported rates of LSIL, which range from 1.1% to 7.0% in the same groups.^6-8 Differences in the length of HPV and LSIL persistence do not completely explain the observed discordance because recent studies have reported that most females who have HPV infection clear it within 12 to 24 months,^9,10 a rate that is similar to the regression rate for LSIL in young women.^11,12 Consistent discrepancies suggest that the development of LSIL is a distinct event in the natural history of HPV infection. Consequently, risks associated with LSIL should be distinct from risks for infection with HPV.