Vulval dermatoses: lichen sclerosus & lichen planus — figure-of-eight distribution, the diagnostic biopsy rule, SCC risk and lifelong surveillance

A 62-year-old woman sits in your clinic describing ten years of vulval itch, splitting on defecation and dyspareunia. She has seen three doctors, been told it is thrush, and been given four courses of clotrimazole. On examination you see the porcelain-white atrophic plaques in a figure-of-eight distribution, with labial fusion, clitoral burying and an introitus narrowed to a finger. Your job is not to treat another imagined thrush — it is to confirm the diagnosis with a vulval biopsy, exclude neoplasia, treat with an ultrapotent topical corticosteroid ointment, and put her on lifelong surveillance. The biopsy rule, the clobetasol regimen, and the 4 percent SCC number are the three things an examiner wants you to defend.[1][3]

Overview and definition

The vulval dermatoses are a group of chronic inflammatory skin conditions affecting the vulva and (frequently) the perianal skin. The 2016 European guideline on vulval conditions groups them as dermatoses (lichen sclerosus, lichen planus, lichen simplex chronicus, eczema, psoriasis), and explicitly separates them from infective conditions, vulvar intraepithelial neoplasia, and the pain syndromes.[5]

Two dermatoses dominate the fellowship exam because they carry a measurable squamous cell carcinoma (SCC) risk and have specific first-line steroid treatment:[1][5]

• Lichen sclerosus (LS) — a chronic inflammatory mucocutaneous disease producing white atrophic plaques in a figure-of-eight distribution; spares the vaginal mucosa; carries an approximately 4 percent lifetime SCC risk.
• Erosive lichen planus (LP) — a chronic inflammatory mucocutaneous disease producing erosions, vaginal adhesions and the vulvo-vaginal-gingival syndrome; carries a lower but elevated SCC risk.