Cytological Analysis of Low-grade Squamous Intraepithelial Lesion with a Histodiagnosis of Cervical Intraepithelial Neoplasia 3 (Severe Dysplasia) Prospectively.

OBJECTIVE: To reanalyze the cytological features of the first cytological specimens of cervical intraepithelial neoplasia 3 (CIN3) (severe) cases that were initially cytodiagnosed as LSIL and followed up for up to 5 years. STUDY DESIGN: Among 14,556.patients in 2009, 236 (1.6%) were cytodiagnosed with low-grade squamous intraepithelial lesion (LSIL). Among those, 128 cases could be histologically diagnosed from 2009 to 2013. Among those 128 cases, 16 were diagnosed as CIN3 (severe). The first cytological specimens of those 16 cases were reanalyzed morphologically. RESULTS: The first cytological specimens of the 16 cases diagnosed as LSIL and histodiagnosed as CIN3 (severe) showed a few small atypical cells in 13 and a cluster of small atypical cells in 1 case. Atypical cells indicating CIN1 were predominant in 14 LSIL cases and there were a few small atypical cells in these cases (LSIL, cannot exclude high-grade squamous intraepithelial lesion [LSIL-H]). CONCLUSION: We show the existence of LSIL-H (LSIL, cannot exclude HSIL) cases, for which biopsy with colposcopy should be applied actively.