VAIN is classified into three grades based on the extent of abnormal cell changes:
VAIN 1: Mild dysplasia involving the lower third of the vaginal epithelium. VAIN 2: Moderate dysplasia involving up to two-thirds of the vaginal epithelium. VAIN 3: Severe dysplasia or carcinoma in situ, involving more than two-thirds of the vaginal epithelium.
