Vulvar intraepithelial neoplasia
VIN; vulvar HSIL (high-grade squamous intraepithelial lesion); usual VIN (uVIN, HPV-related); differentiated VIN (dVIN, non-HPV / lichen-sclerosus-related); Bowen's disease of the vulva (older term)
Vulvar intraepithelial neoplasia (VIN) is squamous cell carcinoma in situ of the vulva, divided into two biologically distinct entities: usual VIN (uVIN / vulvar HSIL), driven by high-risk human papillomavirus (especially HPV-16) and presenting in younger women as multifocal, often pigmented papules and plaques; and differentiated VIN (dVIN), arising in a background of lichen sclerosus or lichen planus in older post-menopausal women as subtle thickened, erythematous or leukoplakic plaques. The two have very different progression risks: uVIN progresses to invasive SCC in ~10% over years, while dVIN has a much higher (32–86%) and more rapid progression to invasive vulval SCC. Diagnosis requires biopsy and management is best coordinated through a vulval MDT.
Subtypes
- Usual VIN (uVIN / vulvar HSIL) — HPV-driven (especially HPV-16). Younger women (30s–50s); multifocal pigmented or red papules / plaques; smoking and immunosuppression are key cofactors. Lifetime invasive risk ~10% (treated) / ~25% (untreated).
- Differentiated VIN (dVIN) — non-HPV; arises within lichen sclerosus or lichen planus. Older post-menopausal women; subtle thickening, leukoplakia or erythema; progression to invasive SCC in 32–86% over a few years if untreated. Most under-diagnosed and most aggressive form.
- Bowenoid papulosis — small multiple pigmented HPV-driven papules in young adults; histologically resembles VIN but generally regresses; see monograph.
Clinical features
- Pruritus, soreness, dyspareunia, bleeding, dysuria.
- Asymptomatic in some — incidental finding at examination.
- uVIN: multifocal pigmented or red papules/plaques on vulva, perineum, perianal skin.
- dVIN: ill-defined leukoplakic, erythematous or hyperkeratotic patch within lichen sclerosus field; any new induration or thickening in LS warrants biopsy.
- Examine the entire anogenital area, vagina and cervix — synchronous lesions common in HPV-related disease.
Diagnosis
- Punch biopsy under local anaesthetic — adequate depth essential to assess for early invasion.
- Multiple biopsies if multifocal or extensive disease.
- Histology distinguishes uVIN (full-thickness atypia, koilocytes, p16 strongly diffuse positive) from dVIN (basal-cell atypia with maturation, p53 aberrant, p16 negative).
- HPV typing in equivocal cases.
- Cervical screening up to date.
- HIV testing in selected patients.
Management
- Refer to vulval MDT.
- uVIN / HSIL:
- Wide local excision with histological clearance is standard for unifocal disease.
- Topical imiquimod 5% — 3 nights/week for 12–16 weeks; complete response 30–60%; useful for multifocal disease, sparing tissue.
- Topical 5-fluorouracil — alternative.
- CO₂ laser ablation — destruction without histology; reserved for confirmed VIN with no suspicion of invasion.
- Photodynamic therapy in selected cases.
- dVIN:
- Wide local excision with clear margins is the only acceptable treatment given high progression risk; topical / ablative therapies inappropriate.
- Concurrent management of underlying lichen sclerosus with ultrapotent topical steroid.
- Lower threshold for re-excision and surveillance.
- Surveillance: lifelong; 3-monthly for 12 months, then 6-monthly. Concurrent cervical screening.
- HPV vaccination has a primary prevention role; may have secondary prevention role to reduce recurrence after treatment for HPV-related disease (emerging data).
Prognosis
uVIN — recurrence ~30%, progression to invasive SCC ~10% (treated) / ~25% (untreated). dVIN — high progression risk (up to 86% if untreated); requires aggressive surgical management. Long-term surveillance is essential. Smoking cessation and treatment of LS reduce recurrence and progression.
References
- Bornstein J et al. The 2015 ISSVD terminology of vulvar squamous intraepithelial lesions. Obstet Gynecol; 2016.
- Edwards SK, Lewis F, Fernando I, Haddon L, Grover D. 2024 British Association for Sexual Health and HIV UK national guideline on the management of vulval conditions. Int J STD AIDS. 2025.
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