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Author: Vanessa Ngan, Staff Writer, 2003. Updated by Hon A/Prof Amanda Oakley and Dr Darion Rowan, Dermatologists, New Zealand, September 2017.
Vulval (or vulvar) intraepithelial neoplasia is a pre-cancerous skin lesion (a type of squamous cell carcinoma in situ) that can affect any part of the vulva. The term vulval intraepithelial neoplasia describes two conditions with different biological behaviour: usual type and differentiated type.
Usual-type VIN is associated with human papillomavirus (HPV) infection, and is also called uVIN and vulval high-grade squamous intraepithelial lesion (HSIL). In this article, we abbreviate the condition as uVIN/HSIL.
Differentiated VIN (dVIN) is associated with inflammatory diseases of the vulva, lichen sclerosus and erosive lichen planus (and not with HPV). It is much less common than uVIN/HSILand accounts for 5% of VIN. Up to 85% of dVIN will progress to SCC if untreated.
Although some women do not have symptoms, uVIN/HSIL and dVIN often present with:
The lesions can occur on any part of the vulva, but are most frequently diagnosed on hair-bearing labia majora, and non-hair–bearing labia minora and posterior fourchette. Most cases of dVIN occur on non-hair bearing skin.
uVIN/HSIL may occur in women of all ages, although an increased number of younger women (even teenagers) are presenting; the average age at diagnosis is about 40 years.
The following factors have been associated with uVIN/HSIL.
One or more flat or thickened, irregular red, white or pigmented plaques on the vulva may suggest a diagnosis of uVIN/HSIL or dVIN. Colposcopy (examination using magnification and a special light) may be used to examine the appearance and extent of the condition. A skin biopsy is required to confirm abnormal epithelial cells within the epithelium, and to identify any invasive cancer.
Warty lesions in postmenopausal women should undergo biopsy, particularly if they do not resolve with simple treatment.
Women with vulval lichen sclerosus and erosive lichen planus should be followed up carefully. Any areas failing to respond to high-potency topical corticosteroids, particularly if hyperkeratotic, should have a biopsy taken to exclude dVIN.
HSIL and dVIN have potential to progress to invasive vulval cancer, whereas LSIL lesions are low risk and are not neoplastic. HSIL-associated cancers tend to be warty in appearance.
LSIL does not always require treatment, but follow-up should be arranged until the lesions resolve, as they sometimes progress to uVIN/HSIL.
There is also a group of younger women with multifocal uVIN/HSIL whose disease resolves spontaneously within a year. Their lesions are usually papular and pigmented. If they persist for longer, treatment should be performed.
uVIN/HSIL and d-VIN are treated to reduce the risk of developing invasive cancer and to alleviate symptoms.
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 (removal of the vulva) is undertaken because of the extent of disease or because of multifocal uVIN/HSIL. Excision is also undertaken for dVIN, which is rarely multifocal but can be more aggressive than uVIN/HSIL.
If invasive cancer is not suspected, laser ablation may be used in some centres. Like surgical excision, it is performed under general anaesthetic.
Medical therapy is reported to be effective in at least some cases of uVIN/HSIL, and is useful for treating a field area prone to multifocal disease. Options include:
None of these medical treatments are officially approved for uVIN/HSIL and they are rarely recommended for dVIN.
Unfortunately uVIN/HSIL recurs in up to half of of patients after treatment. This is more likely if:
Lichen sclerosus associated with dVIN is also a risk factor for recurrence.
Immunisation with HPV vaccine has been shown to decrease the development of uVIN/HSIL as well as cervical cancer and genital warts. Theoretically, nine–valent HPV vaccine could reduce the risk by 80–90%. It does not reduce the risk of dVIN.
Women that have had genital warts or previous uVIN/HSIL should be strongly encouraged to stop smoking.
If left untreated:
Careful follow-up after treatment is essential long term.
Up to 50% of women with uVIN/HSIL develop cervical intraepithelial neoplasia (CIN), anal intraepithelial neoplasia (AIN), vaginal intraepeithelial neoplasia (VAIN) or invasive cancer of the genital tract or anus.
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