Vulvar cancer is a relatively uncommon malignancy, occurring at a rate of 2.2 per 100,000 women per year. Squamous cell carcinoma (SCC) is the most common type of vulvar cancer and is observed in 80% to 90% of cases. There are at least two quite different types of SCC of the vulva. The less common, accounting for about one-third of cases, occurs in relatively young women, is usually preceded by the undifferentiated form of vulvar squamous intraepithelial neoplasia (VIN) and is associated with high-risk human papillomavirus (HPV) infection; the more frequent form develops in elderly patients, is not commonly associated with undifferentiated VIN but is frequently associated with differentiated VIN, lichen sclerosus or squamous hyperplasia, and is generally not linked to HPV infection. Relatively little is known about molecular changes in the genesis of vulvar cancer. Some studies suggest that early p53 mutation may be a defining step only in HPV-negative tumors. A rather small study suggests that mutation in phosphatase and tensin homologue (PTEN) is an early change in a substantial subset of vulvar carcinomas.