High grade squamous intraepithelial lesion of vulva, HPV-associated

**Definition:** Squamous intraepithelial lesions (SILs) of the vulva (also known as vulvar intraepithelial neoplasia [VIN]), HPV-associated, are proliferations of squamous cells driven by HPV infection, showing maturation abnormalities and nuclear hyperchromasia that do not extend beyond the basement membrane.