"Low-grade squamous intraepithelial lesion, cannot exclude high-grade:" TBS says "Don't Use It!" should I really stop it?

Background: The Bethesda System uses a two-tiered approach in the diagnosis of cervical squamous intraepithelial lesions (SILs). Occasionally, Papanicolaou (Pap) tests with evident low-grade SIL (LSIL) also have some features suggestive but not diagnostic of high-grade SIL (HSIL). This study reviews our experience with "Low-grade Squamous Intraepithelial Lesion, Cannot Exclude High-grade" (LSIL-H) and discusses the best approach to report such Paps if the LSIL-H interpretation is abandoned.

Methods: Abnormal Paps were identified between January and December 2014 that had surgical follow-up within 6 months. Their biopsy outcomes were compared. Statistical analysis was performed using Pearson's Chi-square and McNemar tests in SPSS software version 23. Statistical significance was defined as ≤ 0.05.

Results: There were a total of 1049 abnormal Paps with follow-up. High-grade dysplasia/carcinoma (HGD+) was found in 8% of LSIL, 30% of LSIL-H, 52% of atypical squamous cells (ASCs), cannot rule out HSIL (ASC-H), and 77% of HSIL Paps. The detection rate of HGD+ for LSIL-H was between that of LSIL (Pearson's Chi-square test, = 0.000) and ASC-H ( = 0.04). If LSIL-H cases are reported as ASC-H, the rate of HGD+ for the ASC-H category would decrease from 51.5% to 37.4% (McNemar test, = 0.000). Alternatively, if LSIL-H cases are downgraded to LSIL, the rate of HGD+ for the LSIL category would rise from 7.7% to 10.4% (McNemar test, = 0.000). Nearly 86.7% of LSIL-H cases were positive for high-risk HPV (HR-HPV) in comparison to 77.5% of LSILs, 100% of ASC-Hs, and 75% of HSILs. The sample size for HR-HPV and LSIL-H was too small for meaningful statistical analysis.

Conclusions: "LSIL-H" category detects more HGD+ than LSIL, and fewer than ASC-H and HSIL. If LSIL-H is eliminated, Paps with this finding are best reported as ASC-H to ensure that women with potential HGD+ undergo colposcopy in a timely manner. Reporting LSIL-H as LSIL may delay colposcopy since management of LSIL Paps depends on multiple factors (age, HPV status, etc.).