Correlation Between Colposcopic Patterns and Histological Grade of Vaginal Intraepithelial Neoplasia: A Retrospective Cohort Study

Background/aim: Vaginal intraepithelial neoplasia (VaIN) is a rare human papillomavirus (HPV)- related premalignant condition. VaIN lesions are diagnosed histologically through colposcopy-guided biopsies of suspicious areas, conduced by gynecologists with expertise in lower genital tract diseases. The present study aimed to evaluate the accuracy of colposcopy in the diagnosis of VaIN of any grade.

Patients and methods: We conducted a retrospective analysis on a cohort of 149 women diagnosed with low grade (LG)-VaIN (VaIN1) and high grade (HG)-VaIN (VaIN2-3) between 2010 and 2022 at the "Regional Referral Center for Prevention, Diagnosis and Treatment of HPV-related Genital Disorders", Ospedale Maggiore Policlinico, Milan, Italy. All women had been referred to our center for an abnormal Pap smear or as part of routine follow-up of other HPV-related diseases and had undergone a vaginal biopsy under colposcopic guidance.

Results: The distribution of the histological grades of VaIN lesions was the following: 62 women (41.6%) were diagnosed with VaIN1, 51 (34.2%) with VaIN2, and 36 (24.2%) with VaIN3. Grade II (major) abnormal colposcopic patterns were recorded in 71 cases (47.7%) and were more commonly observed in women with VaIN3 (80.6%). However, we found a poor and not statistically significant association between colposcopic and histological grade of VaIN. The sensitivity, specificity, positive predictive value, and negative predictive value of colposcopy for histologically confirmed VaIN were 56.3%, 64.5%, 69% and 51.2%, respectively. The overall diagnostic accuracy of colposcopy was 59.7%.

Conclusion: Colposcopy-guided biopsy plays an important role in the diagnosis of VaIN and in the distinction between low and high-grade lesions. Our data show that major colposcopic abnormalities moderately correlate with HG-VaIN and that grade I colposcopic findings do not exclude HG-VaIN, especially VaIN2. Targeted biopsies of suspicious vaginal areas must be performed in all women with an abnormal Pap smear.