Vulvar dysplasia, or vulvar intrapepithelial neoplasia (VIN), is abnormal changes in the skin of the vulva. The vulva describes a women’s outside genital structures, and includes the area outside of the opening of the vagina. The vulva has the following parts:
- The opening of the vagina with glands that produce lubrication.
- Two skin folds called the outer and inner lips of the vagina. The outer lips (labia majora) is the most common site of vulvar dysplasia. The inner lips (labia minora) are smaller and located inside of the labia majora.
- The clitoris is a sensitive tissue at the top of the vulva where the two lips meet.
- The mons pubis is the area in front of the pubic bone.
- The perineum is the area between the vulva and anus.
Traditionally, vulvar dysplasia was classified as mild, moderate or high grade, depending on the severity of the abnormal changes. Although this classification system is still commonly used, the International Society for the Study of Vulvovaginal Disease (ISSVD) has officially replaced it with a new classification system. In the new classification system, only high grade vulvar dysplasia is classified as vulvar intraepithelial neoplasia (VIN). VIN is then subdivided into “usual type” VIN, also known as vulvar high grade squamous intraepithelial lesion (vulvar HSIL), and “differentiated VIN”. These two types of VIN have different risk factors.
Most cases of VIN can be cured with proper treatment and follow-up. If left untreated, VIN can sometimes progress to vulvar cancer.
Although vulvar cancer is rare, VIN is becoming more common. According to the U.S. Surveillance, Epidemiology, and End Results program, VIN is now four times more common than it was in the 1970s. VIN is usually seen in women in their 40s.