Evidence for increasing usage of low-grade squamous intraepithelial lesion, cannot exclude high-grade squamous intraepithelial lesion (LSIL-H) Pap test interpretations

Background: Pap test (PT) interpretations of low-grade squamous intraepithelial lesion (LSIL), cannot exclude high-grade squamous intraepithelial lesion (HSIL), or LSIL-H, are used in many laboratories; however monitoring its usage for quality assurance purposes is understudied.

Methods: PTs from 2005 to 2010 were collected, and yearly frequencies of LSIL, HSIL, LSIL-H, and atypical squamous cells, cannot exclude HSIL (ASC-H) as a function of total PTs and total squamous intraepithelial lesions (SILs) were calculated. Two-year risk of cervical intraepithelial neoplasia 2 (CIN2) or worse (CIN2+) and CIN 3 or worse (CIN3+) was calculated.

Results: A total of 352,220 PTs were identified including 17,301 abnormal PTs. LSIL-H usage increased from 2005 to 2010 (from 0.28% of total PTs in 2005 to 0.61% in 2010, P < .01; from 5.8% of total SILs in 2005 to 12% in 2010, P < .001). HSIL usage decreased significantly from 2005 to 2010 (from 0.7% of total PTs in 2005 to 0.48% in 2010, P = .048; from 14.5% of total SILs in 2005 to 9.5% in 2010, P < .01). Usage of LSIL and ASC-H did not change. Two-year risk of CIN2+ and CIN3+ for HSIL increased significantly from 2005 to 2010 (P < .01). Two-year risk of CIN2+ and CIN3+ for LSIL-H did not change significantly from 2005 to 2010.

Conclusions: The frequency of LSIL-H interpretations is significantly increasing at our institution, with a significant decrease in HSIL interpretations over the same period. Two-year risk of CIN2+ and CIN3+ for HSIL increased significantly as usage of LSIL-H increased and that of HSIL decreased. Laboratories using LSIL-H may benefit from monitoring its frequency to ensure its appropriate use. Cancer (Cancer Cytopathol) 2014;122:123-7. © 2013 American Cancer Society.