**1. Introduction**

Vaginal Intraepithelial Neoplasia (VAIN) is a rare premalignant lesion of the female lower genital tract, approximately 100-fold less common than cervical squamous intraepithelial lesions [1–3], with an estimated incidence of 0.2–2 per 100,000 women/year [4,5]. The prevalence of VAIN has recently increased due to improvements in screening methods, such as cytology and Human Papillomavirus (HPV) testing [5].

HPV infection is the fundamental etiological factor for the development of VAIN. However, other risk factors have been identified and investigated over time, including young age at first intercourse, a large number of sexual partners, cigarette smoking, immunosuppression, past or concurrent diagnosis of cervical or vulvar preinvasive or invasive lesions, previous hysterectomy for cervical intraepithelial neoplasia (CIN) or cervical cancer, prior radiotherapy, and a history of in utero exposure to diethylstilbestrol [6–8]. Recently,

**Citation:** Iacobone, A.D.; Radice, D.; Guerrieri, M.E.; Spolti, N.; Grossi, B.; Bottari, F.; Boveri, S.; Martella, S.; Vidal Urbinati, A.M.; Pino, I.; et al. Which Risk Factors and Colposcopic Patterns Are Predictive for High-Grade VAIN? A Retrospective Analysis. *Diagnostics* **2023**, *13*, 176. https://doi.org/10.3390/ diagnostics13020176

Academic Editor: Dah Ching Ding

Received: 31 October 2022 Revised: 24 December 2022 Accepted: 30 December 2022 Published: 4 January 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

more attention has also been paid to the potential role of the vaginal microbiota, whose composition is influenced by hormonal status and changes during the development and progression of VAIN [9]

According to the depth of vaginal epithelium involved by dysplasia, VAIN is usually classified into grades 1, 2 or 3. The 2014 WHO classification of VAIN replaced the previous three-tiered system and recognizes only two categories: low-grade VAIN (VAIN1 or vaginal low-grade squamous intraepithelial lesion, LSIL) and high-grade VAIN (VAIN2-3 or vaginal high-grade squamous intraepithelial lesion, HSIL) [10,11]. VAIN1 is the result of a transient low-risk (LR) or high-risk (HR) HPV infection, with a high rate of spontaneous regression within 2 years. High-grade VAIN is due to a persistent and transforming HR-HPV infection and has a higher potential for recurrence and progression towards invasive vaginal carcinoma [12]. Since the risk of progression of VAIN2 to invasive cancer is still under discussion and should be intermediate between VAIN1 and VAIN3, some authors still consider VAIN2 as a separate category [13,14].

VAIN mostly occurs in women over 60 years of age, who are commonly asymptomatic but sometimes report vaginal discharge or bleeding [15]. Furthermore, post-menopausal women may be at increased risk of VAIN due to Lactobacillus depletion, overgrowth of anaerobic species and increased frequency of bacterial vaginosis, which have been indicated as agents responsible for delayed HPV clearance and subsequent carcinogenic progression [9,16].

The diagnosis is usually made by colposcopic-guided biopsy of suspicious vaginal lesions. After an abnormal cervical screening test with no lesion identified on the cervix, great attention should be paid to the complete evaluation of the vagina. Vaginal colposcopy is quite challenging, often due to vaginal dystrophy in post-menopausal women. In addition, colposcopic patterns of VAIN are highly heterogeneous and not very specific, thus resulting in a lack of correlation between colposcopy and histology, unlike CIN [17,18]. Nevertheless, few previous studies have investigated the potential link between colposcopic findings and the histopathologic grade of VAIN, in order to improve the predictive role of the colposcopic examination for treatment management [19,20].

The aim of the present study was to identify the potential risk factors for the development of VAIN to evaluate the diagnostic accuracy of colposcopy in relation to the histological grade of VAIN and to investigate any correlation between clinical and colposcopic features and high-grade VAIN.
