Vulval intraepithelial neoplasia
What is vulval intraepithelial neoplasia?
Vulval (or vulvar) intraepithelial neoplasia is a pre-cancerous skin lesion of any part of the vulva. Vulval intraepithelial neoplasia (VIN) is now also called vulval squamous intraepithelial lesion (SIL). In this article, we abbreviate the condition as VIN/SIL.
VIN/SIL was previously known as Bowen disease of the vulva, but this term is no longer used.
VIN/SIL is not invasive cancer but vulval squamous cell cancer (SCC) occurs in about 15% of women if VIN/SIL is left untreated.
How does VIN/SIL present?
Most women diagnosed with VIN/SIL present with the following symptoms:
- Mild to severe vulval itching
- Mild to severe vulval burning
- One or more slightly raised well defined skin lesions that may be pink, red, brown and/or white in colour.
Why does VIN/SIL occur and who is at risk?
VIN/SIL may occur in women of all ages, although currently an increased number of younger women (even teenagers) are presenting with the condition. The average age of women with VIN/SIL is 45–50 years.
The following factors have been associated with VIN/SIL:
- HPV causes half of all cases of VIN/SIL. VIN/SIL also causes genital warts and other genital cancers (cervical cancer, vaginal cancer and anal cancer). Only oncogenic types of HPV (especially types 16 and 18) are associated with VIN, and these don't always cause visible warts. About half of women with VIN/SIL also have a history of abnormal cervical smears or cancer
- Smoking; it is thought that the cancer promoting agents in cigarettes are concentrated in the skin of the lower genital tract
- Immunosuppression by disease or medications
- Vulval inflammatory skin disease, particularly lichen sclerosus or erosive lichen planus
How is VIN/SIL diagnosed?
The clinical appearance of an irregular red, white or pigmented plaque on the vulva may suggest a diagnosis of VIN/SIL. Colposcopy (examination using magnification and a special light) may be used to see the extent of the condition. A skin biopsy is required to confirm the diagnosis and identify invasive cancer. Warty lesions in postmenopausal women should undergo biopsy, particularly if they do not resolve with simple treatment.
Classification of VIN/SIL
|1. Low grade squamous intraepithelial lesion (flat condyloma or HPV effect)|
|2. High grade squamous intraepithelial lesion (VIN usual type)|
|3. Intraepithelial neoplasia, differentiated-type|
High-grade and differentiated-type SIL have potential to progress to invasive SCC, whereas low-grade lesions are low risk and should not be considered neoplastic.
What treatments are available for VIN/SIL?
Low-grade VIN/SIL does not always require treatment, but follow-up should be arranged until the lesions resolve as they sometimes progress to high-grade VIN/SIL.
High grade and differentiated VIN/SIL lesions are treated to reduce the risk of developing invasive cancer. The aim is to remove all affected tissue with a margin of apparently unaffected tissue. This may be done by surgical excision. Sometimes a complete vulvectomy is undertaken because of the extent of disease or because of several independent areas of VIN/SIL.
If cancer is not suspected, laser ablation may be used in some centres, and is usually carried out under a general anaesthetic.
Medical therapy reported to be effective in at least some cases of VIN/SIL, and is useful for treating a field area prone to multifocal disease. Options include:
- Imiquimod cream, applied 3 times weekly for 12 to 20 weeks. This results in red, inflamed and eroded tissue often accompanied by considerable discomfort.
- 5-fluorouracil cream, applied twice daily for several weeks. This causes quite severe inflammation (several weeks) and will not be tolerated by all women. It is less effective than imiquimod cream.
- Photodynamic therapy (PDT) requires specialised equipment and can also be very painful.
- Cidovir has been described to be useful in some patients.
None of these medical treatments are officially approved for VIN/SIL. Unfortunately recurrence of VIN/SIL occurs in at least one-third of patients. This is more likely if:
- The patient is immune suppressed
- The lesion was incompletely removed (positive margins on pathological report)
- Multifocal disease
Prevention of VIN/SIL
Women that have had genital warts or previous VIN/SIL should be strongly encouraged to stop smoking.
What is the outcome for women with VIN/SIL?
If left untreated, low-grade VIN/SIL may go away by itself (especially the type of low-grade VIN/SIL previously known as Bowenoid papulosis). High-grade VIN/SIL may turn into an invasive cancer in later years. On average it takes well over a decade for HPV-associated usual VIN/SIL to progress to cancer, but cancer may develop more rapidly in differentiated VIN/SIL.
Careful follow-up after treatment is essential long term. VIN/SIL may recur, particularly if excision margins are inadequate. Follow-up every 6 to 12 months is recommended for at least 5 years after surgery for VIN/SIL.
Up to 50% of women with VIN/SIL develop cervical intraepithelial neoplasia (CIN), anal intraepithelial neoplasia (AIN), vaginal intraepeithelial neoplasia (VAIN) or invasive cancer of the genital tract or anus. It is particularly important to have regular cervical smears.