Vulvar intraepithelial neoplasia (VIN)

This page was reviewed under our medical and editorial policy by

Ruchi Garg, MD, Chair, Gynecologic Oncology, City of Hope Atlanta, Chicago and Phoenix

This page was reviewed on January 21, 2022.

Precancerous changes that occur in the surface layer of cells of the vulva are referred to as vulvar intraepithelial neoplasia (VIN). These abnormal cells develop slowly, and grow over the course of several years. In some cases, they may become cancerous (squamous cell carcinoma of the vulva). However, most cases of VIN don’t turn into vulvar cancer.

Based on the appearance of the cells and lesions present, vulvar intraepithelial neoplasia is classified as either usual-type VIN or differentiated-type VIN.

What causes vulvar intraepithelial neoplasia?

The specific cause of vulvar intraepithelial neoplasia is not always known, but the type of VIN may lead the care team to pinpoint a potential cause.

Usual-type VIN is caused by a human papillomavirus (HPV) infection and is more commonly found in women younger than age 50. It may develop into invasive vulvar squamous cell carcinoma. Some doctors grade usual-type VIN as VIN1, 2 or VIN3, with ascending numbers signifying increased severity.

Differentiated-type VIN isn’t caused by HPV infection, but is linked to conditions of the skin that affect the vulva called lichen sclerosus. This type of VIN is more commonly found in women older than age 60. As with usual-type VIN, it may develop into invasive vulvar squamous cell carcinoma.

Vulvar intraepithelial neoplasia symptoms

VIN may not cause any symptoms, but if symptoms do occur, they may include:

  • Itching that doesn’t resolve
  • Thicker skin
  • Skin that’s lighter or darker in color than nearby skin

Vulvar intraepithelial neoplasia treatment

In some cases, the care team may manage VIN by observing it over time to see whether it changes, while other situations may warrant treatments including:

  • Topical creams
  • Surgery to remove the affected tissue
  • Laser ablation to destroy the affected tissue

VIN and cancer risk

While having vulvar intraepithelial neoplasia may increase the risk for developing vulvar cancer, it doesn’t guarantee that a woman will develop it. The risk for developing cancer is higher with VIN3 than with VIN1 or 2, but monitoring and treatment may greatly decrease the risk.

Vaginal intraepithelial neoplasia (VAIN)

Vaginal intraepithelial neoplasia differs from VIN in that it affects the vagina’s inner lining. It is not cancer, but is considered a risk factor for developing vaginal cancer. VAIN is believed to affect fewer than one woman per 100,000 in the United States, and is most common between the ages of 43 and 60.

As with VIN, most cases of vaginal intraepithelial neoplasia are linked to HPV infection. Other risk factors include cigarette smoking, prior radiation treatment and conditions that lead to a deficient immune system.

VAIN may not cause symptoms, but when it does, they may include bleeding after sexual activity or unusual discharge. 

Treatment for vaginal intraepithelial neoplasia is similar to that of VIN, and may include topical therapy, surgical excision or laser ablation. In other cases, the care team may manage VAIN through frequent observation rather than actively treating it.

Getting an HPV vaccine is one of the most important ways to protect against developing VIN and VAIN. Some estimates say that HPV vaccination could prevent 70 percent of VAIN diagnoses. 

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