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Vulval intra-epithelial neoplasia (VIN) is a skin disorder that affects the vulva. Some of the skin cells in one or more areas of the vulva become abnormal, and change in their appearance. Note: VIN is not a cancer. The word neoplasia is sometimes used when talking of various cancers but its strict definition is an abnormal multiplication of cells.

What does VIN mean?

It is called VIN as:

  • Vulval means affecting the vulva.

  • Intra-epithelial means that the condition is limited to within the skin cells (epithelium is a medical word for the top layer of skin).

  • Neoplasia means abnormal growth or multiplication of cells.

VIN is classed as a precancerous condition because over time, the cells of VIN in some affected women become cancerous. VIN can develop anywhere on the vulva. It may affect only one patch, or develop in a number of different parts of the vulva.

It is similar to the abnormal cells that are found in some women following cervical screening. The abnormal cells that may be found in this situation are also precancerous and not actually cancer.

VIN is subdivided (classified) into three groups:


  • VIN, usual type. This type is associated with the human papillomavirus (HPV).

  • VIN, differentiated type. This is much less common than VIN, usual type. This type is not usually associated with HPV but may develop in conjunction with another skin disease such as lichen sclerosus.

  • VIN, unclassified type. This is rare.

Note: Before 2004, VIN was classified into VIN 1, 2 and 3.

What causes VIN?

The exact cause of VIN is not known.

VIN, usual type, is strongly linked to HPV. There are over 100 different types (strains) of HPV. Two types, 16 and 18, are particularly associated with the development of most cases of VIN. Type 31, and possibly some other types, may also be associated with VIN.

Note: some other types of HPV cause common warts and verrucas. These types of HPV are not associated with VIN.

The types of HPV associated with VIN are nearly always passed on by having sex with a person carrying the virus. An infection with one of these types of HPV does not usually cause symptoms. You cannot tell if you or the person you have sex with are infected with one of these types of HPV. In some women, the types of HPV that are associated with VIN affect the cells of the vulva. This makes them more likely to become abnormal which may later (usually years later) turn into VIN.

Note: HPV infection is very common but within two years, 9 out of 10 infections with HPV will clear completely from the body. And, even if it remains in the body, most people with HPV do not go on to develop VIN. So, although most cases of VIN are associated with HPV, most women who are infected with HPV do not develop VIN.

Other factors may also play a role in causing VIN, these include smoking and anything that depresses the immune system.

VIN, differentiated type develops more commonly in women who have another vulval skin disease such as lichen sclerosus or lichen planus.

A similar condition to VIN can occur on other nearby parts of the body. When it affects the cervix it is called cervical intra-epithelial neoplasia (CIN) and this is much more common than VIN. The cervical screening test is designed to pick up the abnormal cells. Vaginal intraepithelial neoplasia (VAIN) and anal intra-epithelial neoplasia (AIN) are uncommon. The cause of most cases of CIN, VAIN and AIN are also thought to be associated with infection by the HPV. If you have VIN, you have a higher than average risk of also developing one of these other related conditions.

How common is VIN?

VIN is uncommon (it is difficult to give exact figures). However, in recent years the number of cases seems to be rising gradually. Most women affected are over the age of 40. The average age of diagnosis is about 45-50 years. But, it can sometimes affect younger women and, rarely, can even affect teenagers.

What are the symptoms?

About 1/3 of women have no symptoms and the abnormal changes will only be seen if the skin is examined. These changes include areas of red or white skin which can be thickened. Otherwise itch is the most common symptom and it may become severe. Other symptoms that may develop include soreness, burning or tingling in the vulva. Having sex may be painful. These symptoms are also caused by other conditions so it is important to see a doctor.

Does it need to be treated?

If left untreated, in a small number of cases VIN may go away by itself. However, most cases of VIN do not and because of the risk that it may turn into cancer — treatment is usually advised. It is also important to remember that many cases of VIN do not develop into cancer. However, it is not possible to predict which cases will and which ones won’t. On average, it usually takes a long time — years even, to develop into cancer.

What is the prognosis (outlook)?

All of the above treatments have a good chance of clearing VIN. However, with any treatment, even when successful, there is a chance that the VIN will return at some point in the future. This is why if you have VIN you should have regular follow-up assessments with a doctor, even when treatment has been successful. This is typically a review appointment every 6-12 months. But, if you notice any symptoms or changes in your vulva between follow-up appointments, see your doctor promptly. Don’t wait for the next routine appointment.

Research continues to determine which treatment is likely to give the best chance of cure and least chance of a recurrence. Also, to look for newer, better treatments. For example, small research trials that looked at combining treatments (imiquimod followed by three doses of HPV vaccine, and imiquimod combined with PDT) showed promising results.

Can VIN be prevented?

The HPV vaccine has recently been introduced for girls from the age of 12 in the UK. Studies have shown that the HPV vaccine usually works very well to prevent HPV infection. As discussed earlier, HPV infection is a major factor in the development of VIN. The vaccine has been shown to work better for people who are given the vaccine when they are younger, before they are sexually active, compared with when it is given to adults. It is likely that the number of cases of VIN will greatly reduce by the time the girls being vaccinated today reach adulthood – the age when VIN usually develops.

Does smoking affect VIN?

It is thought that damaging chemicals from cigarette smoking may concentrate in the skin of the vulva and cervix, which can increase the risk of developing VIN and related disorders. If you smoke, giving up reduces your chance of developing VIN.

If you have been treated for VIN and you smoke, giving up smoking can reduce your risk of VIN recurring in the future. For example, one research study concluded that women who continued to smoke after treatment for VIN were much more likely to have persistent or recurrent vulval disease compared with non-smokers.

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