Vulvar Psoriasis

Vulvar psoriasis is psoriasis involving the vulva, either alone or with skin psoriasis. It is often the inverse (flexural) type, with smooth red plaques that lack the thick scale seen elsewhere.

• It is a chronic, relapsing immune-mediated disease.
• Triggers include friction, infection, stress, and some drugs.
• Treatment is by emollients and weak to moderate topical steroids, with caution for the thin vulval skin.

Well-demarcated, bright red, shiny plaques on the labia majora, mons and genitocrural folds, with little or no scale.

• Itching, burning, soreness and fissuring.
• Plaques elsewhere on the scalp, elbows, knees and nails support the diagnosis.
• Differential diagnosis: candidiasis, tinea cruris, irritant or allergic dermatitis, seborrhoeic dermatitis, lichen sclerosus, extramammary Paget disease, vulval intraepithelial neoplasia.
• Complications: secondary candidal or bacterial infection, fissures, dyspareunia, psychological distress.

Diagnosis is clinical, with exclusion of candidiasis and tinea.

• Clinical diagnosis with skin and nail examination.
• Potassium hydroxide 10 percent preparation or swab culture to exclude candidiasis; skin scrapings for tinea.
• Biopsy if the plaque is atypical, persistent, ulcerated or does not respond.
• Random blood glucose; HIV test if severe or sudden.

Use emollients and the weakest effective topical corticosteroid, with care for thin vulval skin.

• Supportive: avoid irritants; wash with water or soap substitute; apply emollient (petroleum jelly or emulsifying ointment) 2 to 3 times daily; cotton underwear; avoid friction.
• Pharmacological: mometasone 0.1 percent ointment applied thinly once daily for 2 weeks, then on alternate days for 2 weeks, then twice weekly. For mild disease or children, hydrocortisone 1 percent cream twice daily for up to 14 days. Steroid-sparing: tacrolimus 0.1 percent ointment twice daily where available. Calcipotriol is not used on the vulva because it irritates. Secondary candidiasis: clotrimazole 1 percent cream twice daily for 2 weeks. Secondary bacterial infection: flucloxacillin 500 mg oral 6-hourly for 5 to 7 days. Extensive or severe psoriasis: refer for methotrexate or phototherapy.
• Procedures: punch biopsy under 1 percent lignocaine (maximum 3 mg/kg) when diagnosis is uncertain.
• Special groups: in pregnancy use emollients and mild to moderate steroids, and avoid methotrexate. In children use hydrocortisone 1 percent for up to 7 days.
• Red flags: ulcer, white plaque, bleeding, no response in 4 to 6 weeks, widespread pustular disease.
• Follow-up: review at 4 weeks, then every 3 to 6 months; reduce steroids gradually to avoid skin thinning.