Vaginal intraepithelial neoplasia (VAIN) is a condition that describes premalignant histological findings in the vagina characterized by dysplastic changes.
[2] VAIN can be detected by the presence of abnormal cells in a Papanicolaou test (Pap smear).
[3] In VAIN 1, a third of the thickness of the cells in the vaginal skin are abnormal, while in VAIN 3, the full thickness is affected.
[3] VAIN 3 is also known as carcinoma in-situ, or stage 0 vaginal cancer.
[4] Vaccinating with HPV vaccine before initial sexual contact has been shown to reduce incidence of VAIN.