High-Grade Vaginal Intraepithelial Neoplasia: Clinical Profile, HPV Vaccination Status, and Treatment Outcomes at Two Italian Referral Centers

<b>Background</b>: There is limited available data about the natural history and clinical characteristics of patients affected by high-grade vaginal intraepithelial neoplasia (or vaginal intraepithelial neoplasia 2/3 or vaginal high-grade squamous intraepithelial lesion, HSIL). The aim of the study was to review clinical characteristics and treatment outcomes of a large cohort of patients with vaginal HSIL. <b>Methods</b>: A retrospective analysis was performed for patients with histologically confirmed VaIN 2/3 treated at two Italian referral centers from 2003 to 2022. Demographics, referring cytology, associated cervical and vulvar HSIL treatment modalities, follow-up visits, and vaccination status were recorded. The primary outcome was risk of recurrence; the secondary outcome was risk of progression to invasive carcinoma after treatment. <b>Results</b>: 323 women were included in the analysis: 69.7% (225) had VaIN2, and 30.3% (98) had VaIN3. Mean age at diagnosis was 55.43 years (range 24-93 years). 20.4% had a previous hysterectomy, mainly for cervical intraepithelial neoplasia (CIN)/invasive squamous carcinoma (64.6%). In total, 55.2% underwent ablative therapy, and 44.8% underwent excisional treatment. Over a mean follow-up of 62.43 months, 22.0% of patients recurred as vaginal HSIL. At univariate analysis older age, VaIN grade 3, previous hysterectomy, associated cervical lesions, associated vulvar HSIL, and excisional treatment were significantly associated with increased risk of recurrence. At multivariate analysis, only hysterectomy and excisional treatment maintained significance. Five patients progressed to invasive vaginal carcinoma, with a median time to invasion of 87.1 months. <b>Conclusions</b>: The risk of recurrence of vaginal HSIL is higher in patients treated with excisional methods and/or those who have undergone hysterectomy for both benign and preinvasive lesions. Long-term follow-up is essential to monitor clinical outcomes and prevent disease progression.