	Headline
Etiology	Epidermal hyperproliferation + inflammatory infiltration. Can be triggered by ACE inhibitors, ß-blockers, Lithium, antimalarials, tetracyclines, infliximab, NSAIDs, alcohol.
Epidemiology	1-3% of world (and UK population similarly )
Clinical presentation	well-defined silvery plaques on extensor surfaces May have joint involvement
Pathogenesis
Diagnostic investigations
Management	Stepwise approach: - topical Vit D + betamethasone e.g. Dovobet → stop corticosteroids once skin is clear - Top Vit D BD 8-12w → corticosteroid/coal tar - systemic: retinoids (acitretin ⚠ teratogenic; risks with immunosuppression e.g. hx of malignancy), MTX for joint involvement, ciclosporin if widespread/acute - biologics: anti-TNF, anti-IL-17, anti-IL-23 - Lifestyle: stop smoking/alcohol
Prevention

psoriatic arthritis

	in 10% of patients with psoriasis
Etiology	seronegative inflammatory arthritis. Associated with HLA-B27. May be triggered by Group B Strep, HIV, trauma, stress (see psoriasis).
Epidemiology
Clinical presentation	Mono/oligoarthritis, enthesitis, dactylitis, fatigue; neck/back + DIP (individual fingers) commonly affected; psoriatic nail changes Not always skin signs but check hair line, intergluteal cleft. Ddx:
Pathogenesis
Diagnostic investigations	Radiology: “pencil in cup”
Management	➥ limited disease: NSAIDs (e.g. naproxen, diclofenac); progressive disease: NSAIDs + sulfasalazine/methotrexate/ciclosporin ➥ physiotherapy ➥ If failed 2 DMARDs, consider TNF-alpha inhibitors/monoclonal Abs e.g. etanercept, adalimumab

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