Presence of koilocytosis in low‐grade smears of high‐risk HPV‐positive women is a negative predictor for cervical intraepithelial neoplasia grade 3 or more

Objective The Netherlands converted to high‐risk (hr)HPV‐based screening in 2017. An increase in referral of hrHPV‐positive women with low risk for cervical intraepithelial neoplasia grade 3 or more (CIN3+) is anticipated and reduction of unjustified referrals will have priority. The relevance of koilocytosis in relation to the underlying risk of high‐grade CIN in a primary HPV screening setting is unclear. The aim was to investigate whether the risk for CIN3+ differs between hrHPV‐positive atypical squamous cells of undetermined significance (ASC‐US)/low‐grade squamous intraepithelial lesion (LSIL) with or without koilocytosis. Methods Retrospective cohort study, using data from the Dutch national pathology database (PALGA). The population was 1201 hrHPV‐positive women with cytological diagnosis of ASC‐US/LSIL. Reporting of koilocytosis was assessed as well as detection rates of CIN1 or less, CIN2 and CIN3+ for ASC‐US/LSIL cytology stratified by presence or absence of koilocytosis. Crude and adjusted odds ratios were determined. Results Koilocytosis was present in 40.1% of ASC‐US and 45.9% of LSIL cases. CIN3+ is significantly less often found when koilocytosis is present (7.8% for hrHPV‐positive ASC‐US with‐ vs 15.8% without koilocytosis). For hrHPV‐positive LSIL this was 11.7% vs 20.2%. The crude and adjusted odds ratios for CIN3+ was 0.45 for hrHPV‐positive ASC‐US and 0.52 for hrHPV‐positive LSIL. Conclusions The presence of koilocytosis is a negative predictor of CIN3+. The risk of hrHPV‐positive ASC‐US with koilocytosis is in the same range as hrHPV‐positive/cytology negative cases and in a setting of primary hrHPV screening these cases could be followed conservatively by repeat cytology. The results should be confirmed by the first data from the Dutch HPV‐based screening programme. We investigated the relevance of koilocytosis in ASC‐US samples and found that the presence of koilocytosis is a negative predictor of CIN3+. High risk HPV‐positive ASC‐US showing koilocytosis could therefore be followed conservatively by repeat cytology in hrHPV‐based screening.