Vulval intraepithelial neoplasia (VIN) is a skin condition of the vulva. It is not a cancer, but it can turn into cancer if not treated.
What is vulval intraepithelial neoplasia?
Vulval intraepithelial neoplasia (VIN) is a skin disorder that affects your vulva. (See the separate leaflet called Gynaecological Cancer for more information about what and where the vulva is.)
If you have vulval intraepithelial neoplasia, the cells of the skin of part, or several parts, of your vulva become abnormal and change in their appearance. It is called vulval intraepithelial neoplasia because:
- Vulval means affecting the vulva.
- Intraepithelial 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 overproduction (proliferation) of cells.
Note: vulval intraepithelial neoplasia is not a cancer. The word neoplasia is sometimes used when talking of various cancers but its strict definition is an abnormal proliferation of cells. With VIN the cells are not cancerous.
However, in time, the cells of VIN in some affected women may become cancerous. So, vulval intraepithelial neoplasia is classed as a pre-cancerous condition. (This is similar to the abnormal cells that are found in some women following cervical screening - previously called the cervical smear test. The abnormal cells that may be found in this situation are also usually pre-cancerous and not actually cancer.) Vulval cancer is usually a squamous cell carcinoma (see the leaflet on Vulval Cancer for more information).
There are three types of VIN:
High-grade squamous intraepithelial lesion (HSIL)
- This is the most common type of VIN. Many women who have it have ongoing infections with high-risk types of HPV (see below). It occurs mainly in women aged 35 to 49 and is more common in women who smoke or have a weak immune system.
- Treatment is usually recommended for HSIL because there is a risk that the abnormal cells may develop into cancer over time, but the risk is low.
Low-grade squamous intraepithelial lesion (LSIL)
- LSIL is usually a mild abnormality, and is usually caused by low-risk types of the human papillomavirus (HPV). These low-risk types can cause warts in this area. They are not cancerous and usually go away without treatment.
- Regular follow-up appointments may be needed to check that the lesions are getting better.
Differentiated VIN (dVIN)
- This is an uncommon type of VIN and tends to develop in women between 50 and 60 years of age. It is rarely linked to HPV infection.
- It is often found in women who have a vulval condition called lichen sclerosus (inflammation of the skin, causing itchy, white patches).
- Differentiated VIN has a higher risk of developing into a cancer than high-grade squamous intraepithelial lesion (HSIL). Therefore surgery is usually the best treatment for dVIN.
What causes vulval intraepithelial neoplasia?
The exact cause of vulval intraepithelial neoplasia is not known. However, many cases are strongly linked to HPV. There are over 100 different types (strains) of HPV. Two types, types 16 and 18, are particularly associated with the development of most cases of VIN. These types of virus may cause abnormal cells or even cancer in the neck of the womb (cervix), vagina, vulva or back passage (anus).
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 vulval intraepithelial neoplasia are nearly always passed on by having sex with an infected person. An infection with one of these types of HPV does not usually cause symptoms. So, you cannot tell if you are infected, or the person you have sex with is 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.
HPV infection by itself may not directly cause VIN. It may be that other factors are needed in addition to HPV to cause vulval intraepithelial neoplasia. Other factors that may possibly play a role in causing VIN include smoking and anything that weakens the immune system.
How common is HPV?
HPV infection is very common. However, within two years, 9 out of 10 infections with HPV will clear completely from the body. Even if it remains in the body, most people infected with HPV do not go on to develop vulval intraepithelial neoplasia. So, although most cases of VIN are associated with HPV, most women who are infected with HPV do not develop VIN. The HPV vaccination provides protection against usual-type VIN.
VIN, differentiated type, develops more commonly in women who have another vulval condition called vulval lichen sclerosus. It is also sometimes associated with a skin condition called lichen planus. See separate leaflets called Lichen Sclerosus and Lichen Planus.
A similar condition to vulval intraepithelial neoplasia can occur on other nearby parts of the body. When it affects the cervix it is called cervical intraepithelial neoplasia (CIN). This is much more common than VIN, as it is what is looked for during the cervical screening test. Vaginal intraepithelial neoplasia (VAIN) and anal intraepithelial 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.
What are the symptoms of vulval intraepithelial neoplasia?
Sometimes there are no obvious symptoms, particularly when it first develops. So, unless you actually look at your vulva, you may not know vulva intraepithelial neoplasia has developed. However, symptoms eventually usually do develop. A persistent itch in the vulva is the most common symptom. The itch may become severe. Other symptoms that may develop include soreness, burning or tingling in the vulva. Having sex may be painful.
VIN also usually causes a change in the appearance to the affected part or parts of the vulva. These include areas of redness, or white areas of skin. Sometimes affected areas of the vulva develop raised areas of skin.
See a doctor if you have any persistent vulval symptoms or notice any changes to the skin or structures of the vulva. Some of the above symptoms and signs can be caused by various other conditions. Your doctor will be able to examine you and assess you. If your doctor suspects VIN then he or she will refer you to a specialist.
How is vulval intraepithelial neoplasia diagnosed?
The diagnosis can be confirmed by a biopsy of the affected area. A biopsy means a small sample of vulval skin is taken to be examined in the laboratory. The biopsy is usually done after using local anaesthetic to numb the area being sampled. The cells in the biopsy are examined under a microscope to look for the typical cells of vulval intraepithelial neoplasia.
Vulval intraepithelial neoplasia treatment options
The aim of treatment is to remove or destroy all affected tissue. There are various treatment options. Your specialist will advise on the pros and cons of the different options.
The treatment for VIN depends on where the disease is, how large an area is involved and the symptoms it is causing. Some women with VIN have no treatment at all and are kept under regular review by their specialist. This may be recommended if you have large areas of VIN and have no symptoms.
Treatment options include the following:
In many cases, treatment is to have the affected area or areas removed by an operation. The type of surgery depends on the extent of the VIN. Rarely, if the area affected by VIN is extensive, wide local excision is required and the entire vulva may need to be removed (vulvectomy). A skin graft (skin taken from another site in the body) may be needed if this is done.
Imiquimod is a medicine that comes as a cream. You rub it on to affected areas (apply it topically) each day for several weeks. It is used for some women as an alternative to surgery or even after surgery.
Ablation treatments are alternatives to surgery. Ablation means destroying the affected area. It can be done using a high-energy beam (laser) or a tiny electrical current passed through a probe (diathermy).
Photodynamic therapy (PDT) is another treatment which is occasionally used. For this treatment, a medication is either applied topically to the vulva or given as an injection into the bloodstream. The medication is taken up by the abnormal cells and is light-sensitive. A few hours later, a cold laser light is shone at the abnormal cells. This activates the light-sensitive medication, which has an effect of destroying the abnormal cells.
The advantages of PDT and imiquimod (and similar medications) is that, if they work, there is no change to the appearance of your vulva as you would have following surgery.
In some cases, the condition may simply be monitored, as sometimes it settles on its own without the need for treatment. Your specialist will advise on the best treatment for you.
The above treatments aim to cure the condition. However, in the meantime, you may benefit from soothing treatments. For example, whilst awaiting results of samples taken (biopsies) or awaiting treatment. These may help to ease any itch or discomfort but do not cure the condition.
Your doctor may advise you to use a soothing bland cream on your vulva. Sometimes a steroid cream is used which aims to ease any inflammation or itch. Sometimes a local anaesthetic ointment may be advised to ease soreness.
It is also best to avoid using soaps, deodorants, etc, on the vulval skin as these can be irritating. To wash your vulva you can use a bland moisturiser such as emulsifying ointment instead of soap. You can also use the moisturiser to soothe the area as often as necessary.
What is the outlook (prognosis)?
All the above treatments have a good chance of clearing vulval intraepithelial neoplasia.
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. However, 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 the least chance of the condition returning.
Can vulval intraepithelial neoplasia be prevented?
The HPV vaccine has 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 vulval intraepithelial neoplasia. 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.
Smoking and VIN
It is thought that damaging chemicals from cigarette smoking may concentrate in the skin of the vulva and neck of the womb (cervix). This can increase the risk of developing vulval intraepithelial neoplasia 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 returning in the future.
Further reading and references
UK national guideline on the management of vulval conditions; British Association for Sexual Health and HIV. 2014.
van der Meijden WI, Boffa MJ, Ter Harmsel B, et al; 2021 European guideline for the management of vulval conditions. J Eur Acad Dermatol Venereol. 2022 Jul36(7):952-972. doi: 10.1111/jdv.18102. Epub 2022 Apr 12.
Hurt CN, Jones S, Madden TA, et al; Recurrence of vulval intraepithelial neoplasia following treatment with cidofovir or imiquimod: results from a multicentre, randomised, phase II trial (RT3VIN). BJOG. 2018 Jan 16. doi: 10.1111/1471-0528.15124.
Kaushik S, Pepas L, Nordin A, et al; Surgical interventions for high-grade vulval intraepithelial neoplasia. Cochrane Database Syst Rev. 2014 Mar 43:CD007928. doi: 10.1002/14651858.CD007928.pub3.
Reyes MC, Cooper K; An update on vulvar intraepithelial neoplasia: terminology and a practical approach to diagnosis. J Clin Pathol. 2014 Apr67(4):290-4. doi: 10.1136/jclinpath-2013-202117. Epub 2014 Jan 7.