Regression of high-grade squamous intraepithelial lesions in women aged 30 years or younger: a retrospective cohort study.

Abstract

Purpose: To assess the rate and timing of spontaneous regression of high-grade cervical intraepithelial lesions (CIN2/HSIL and CIN3/HSIL) in young women and to identify associated factors.

Methods: This retrospective cohort study included patients aged ≤ 30 years diagnosed with HSIL (CIN2 or CIN3) at the certified dysplasia unit of the Department of Gynecology, University Hospital Erlangen, between April 2014 and November 2025 who underwent observational management. Regression was defined as partial regression (low-grade squamous intraepithelial lesion; LSIL) or complete regression (less than LSIL), with histology as the reference standard.

Results: 45 patients with CIN3/HSIL and 38 with CIN2/HSIL were included. In the CIN3/HSIL cohort, regression was observed in 21 of 45 patients (46.7%), including regression to LSIL in 6 (13.3%) and complete regression in 15 (33.3%) cases. The median time to regression (≤ LSIL) was 236 days (IQR, 126-308 days). The CIN2/HSIL cohort showed even higher regression rates, with partial or complete regression in 24 of 38 cases (63.2%). Regression was associated with HPV clearance in both groups and with HPV16 negativity and HPV vaccination in the CIN2/HSIL cohort. No cases of progression to (micro)invasive disease were observed in either group. The probability of regression did not differ between patients aged ≤ 24 and > 24 years.

Conclusion: In this selected cohort of women aged ≤ 30 years managed conservatively, spontaneous regression of CIN2/HSIL and CIN3/HSIL occurred frequently, particularly during the first year of follow-up, without progression to invasive disease. HPV clearance, HPV16 and vaccination status may help guide patient selection for observational management.