High prevalence of high grade squamous intraepithelial lesions and microinvasive carcinoma in women with a cytologic diagnosis of low grade squamous intraepithelial lesions

OBJECTIVE: To evaluate the histologic nature of low grade intraepithelial l esion (LSIL) in a region with a high prevalence of invasive cervical carcin oma and to propose a management protocol. STUDY DESIGN: Comparing the follow-up of 877 women with LSIL during a 43-mo nth period, taking into consideration the histologic nature determined by c olposcopic biopsy, endocervical curettage, conization or hysterectomy as th e final pathologic diagnosis. RESULTS: During the study period, from July 1994 to February 1998, a total of 128,925 Pap smears were performed at our institute, with 877 (0.68%) dia gnosed as LSIL. Among these, 722 women with CIN1-SIL and 32 with human papi llomavirus-related changes (HPV-SIL) were enrolled in the study. Of the 543 women with CIN 1/squamous intraepithelial lesion, 145 (27%) cases of high grade squamous intraepithelial lesion were disclosed histologically, as wer e 16 (3%) cases of microinvasion. Among those followed at an interval of th ree months with a Pap smear alone, the persistence rate was 46.8%, while th e regression rate was 40%. Thirty-two women with HPV/SIL underwent histolog ic evaluation, revealing 18% CIN 2/3 with no microinvasion. CONCLUSION: A high percentage of CIN 2/3 as well as microinvasive lesions w ill go unnoticed in the abscence of colposcopic evaluation.