Progression of CIN1/LSIL HPV Persistent of the Cervix: Actual Progression or CIN3 Coexistence.

After 4 years of follow-up, only 1.5% (7/475) of the women with LSIL developed CIN3, all within the first two years of follow-up, and were immediately treated. The most likely explanations for "progression" from LSIL to HSIL are (1) actual progression, (2) underdiagnosis of HSIL on initial biopsy, (3) overdiagnosis of HSIL on follow-up biopsy/cone, and (4) CIN3 arose de novo. Analyzing the histological exams of the cones of the 7 cases that progressed to high-grade, we found the coexistence of CIN1 and CIN3 lesions in all cases. Some recent studies have shown that a viral genotype corresponds to different lesions in the same cervix; therefore, CIN1 coexisting with CIN3 does not always indicate progression of CIN1. Other authors have doubted the capacity of LSIL to progress.