The value of duplicate slides on atypical squamous cells, cannot exclude high-grade intraepithelial lesion

Atypical squamous cells, cannot exclude high-grade squamous intraepithelial lesion (ASC-H) category was added to the 2001 Bethesda System. ASC-H accounts for a small percentage (0.2-0.6%) of abnormal Pap smears and includes heterogenous group of lesions. There are more high-grade cervical lesions (30-50%) in ASC-H than ASC-US (10-15%). An accurate Pap diagnosis is crucial for appropriate patient follow-up and treatment. A total of 43 consecutive ASC-H cases were collected from October 2007 to March 2008, and all duplicate and the original slides were reviewed blindly at the end of the study. On review of the duplicate Pap slides, 18 cases had diagnostic SIL cells (15 HSIL, 2 LSIL with ASC-H, and 1 LSIL). The duplicate slides could have potentially changed 18 (41.9%) ASC-H diagnoses to a more definitive SIL diagnosis. On review of the original Pap slides, 8 of these 18 cases also had HSIL cells. Twenty-one follow-up cervical biopsies (21/43, 48.8%) showed 12 CIN 2/3, 4 CIN 1, 1 VAIN 1, 2 cervical polyps, 1 negative for dysplasia, and 1 insufficient for diagnosis. The CIN 2/3 rate was 57.1% (12/21) based on the original ASC-H Pap diagnosis. The CIN 2/3 rates were 80% (8/10) with SIL cells on duplicate slides and 36.4% (4/11) without SIL cases on duplicate slides. Our study suggested that duplicate slides were very useful for further classification of ASC-H, but other ancillary tests might be necessary for some cases. We propose a systematic approach using combined duplicate slides and reflex HPV testing to further classify ASC-H.