Hi all! I was floored to find out that this type of pre cancer existed. Here is my understanding of them: CIN is Cervical Intraepithelial Neoplasia, VAIN is Vaginal Intraepithelial Neoplasia, & VIN is Vulvar Intraepithelial Neoplasia and all are graded as I, II, III with III the most severe and considered adenocarcinoma in situ.