Synopsis
Assess three high-impact psoriasis sites, separate common mimics, collect specimens before masking infection, and match formulation, potency and referral to anatomy and functional burden.
- Scalp psoriasis forms sharply defined plaques with adherent scale, often extending beyond the hairline; part the hair and inspect ears, face, elbows and nails before deciding it is simple dandruff.
- Nail matrix disease causes pitting, ridging or crumbling; nail-bed disease produces salmon or oil-drop change, onycholysis and subungual hyperkeratosis.
- Palmoplantar plaques are thick, sharply bounded and fissured; palmoplantar pustulosis produces recurrent sterile pustules that become yellow-brown and is strongly associated with smoking.
Key red flags
Painful fluctuant swelling, spreading warmth, purulent discharge or fever suggests bacterial infection and requires prompt severity and sepsis assessment.
Rapid nail loss, scarring hair loss, severe fissuring that prevents walking or a changing ulcerated acral lesion needs accelerated assessment rather than repeated empirical topical treatment.
Investigation priorities
Map scalp, nail-unit, palm and sole morphology and search for psoriasis at less symptomatic sites.
Management branches
Confirmed scalp psoriasis without infection or scarring alopecia.
- Part the hair, loosen thick adherent scale with salicylic-acid, oil or emollient preparation where appropriate, then wash out gently rather than picking plaques.
- Apply a potent topical corticosteroid scalp formulation once daily for up to four weeks, directing it onto skin rather than coating hair.
Key medicines
Potent topical corticosteroid scalp formulationApply a thin layer to affected scalp skin once daily for up to 4 weeks, using the formulation and maximum quantity specified for the prescribed product.
Calcipotriol 50 micrograms/g plus betamethasone 0.5 mg/g ointmentApply once daily to affected adult plaque psoriasis for 4 weeks; do not exceed 15 g daily or treat more than 30% body surface area with calcipotriol-containing products.