Evaluation of Low-Grade Squamous Intraepithelial Lesions, Cannot Exclude High-Grade Squamous Intraepithelial Lesions on Cervical Smear

Background : We examined cervicovaginal smears that contained definite low-grade squamous intraepithelial lesion (LSIL) cells and rare atypical cells suggestive of high-grade SIL (HSIL) (ASC-H) or contained borderline dysplastic cells between LSIL and HSIL. Such lesions were classified as LSIL-H. This study aimed to investigate the cytologic and histologic characteristics of LSIL-H category and we evaluated the associated clinical risk. Methods : The histologic outcomes of LSIL-H were compared with those of LSIL and ASC-H. Both the cytologic and histologic findings of LSIL-H that were confirmed as cervical intraepithelial neoplasia 2 (CIN2) or greater (CIN2+) were investigated. Results : LSIL-H accounted for 0.09% of the Pap tests. On the follow-up histology, the most frequent outcome was CIN2, and the risk of CIN2+ was higher than that for ASC-H. In the cases of LSIL-H that was histologically confirmed as CIN2+, most of the atypical cells suggestive of HSIL were cytologically similar to those of CIN2, and the corresponding cervical tissues were characterized by small CIN2+ lesions in a large background of flat condyloma/CIN1. The LSIL-H cases not confirmed on initial colposcopically-directed biopsy required further follow-up. Conclusions : LSIL-H may be a valid diagnostic category with distinctive features that are different from LSIL or ASC-H. LSIL-H needs further follow-up for the proper management.