Psoriasis

Common disorder characterised by red scaly plaque

Epidemiology

• 2% of the population
• Males = Females

Aetiology

• T lymphocyte - driven
• Genetic - polygenic
• Environmental triggers
• Infection
• Drugs, e.g. lithium
• UV light
• Alcohol
• Stress/anxiety

Clinical features

Chronic plaque psoriasis

• Purplish/red scaly plaques, particularly on extensor surfaces
• Scalp frequently involved
• Can occur in areas of skin trauma (Kobner phenomenon)
• 50% associated with nail changes
• Nail pitting
• Distal separation of nail plate (onycholysis)
• Yellow/brown discolouration
• Subungual hyperkeratosis
• If severe, loss of nail plate

Flexural psoriasis

• Occurs in older patients
• Patches
• Groin
• Natal cleft
• Submammary areas

Guttate psoriasis

• Raindrop-like lesions on trunk
• Occurs in children/young adults 2 weeks after a streptococcal sore throat

Arthritis associated with psoriasis

• Bilateral
• DIP joints and PIP joints

Management

• Education and explanation
• Avoid irritants
• Topical steroids
• Calcipotriol (Vitamin D3 analogue)
• Coal tar
• Phototherapy (e.g. PUVA (psoralen + UVA))
• Methotrexate if severe

Complications

Erythroderma

• Widespread inflammation of the skin

Common causes

• Atopic eczema
• Psoriasis
• Drugs, e.g. sulphonamides, gold
• Seborrhoeic dermatitis

Management

• Bed rest
• Liberal IV fluids
• Keep warm
• Emollients
• Beware of sepsis
• Treat/remove the cause

Complications

• High-output cardiac failure
• Hypothermia
• Dehydration
• Hypoalbuminaemia
• Increased basal metabolic rate
• Capillary leak syndrome