What is psoriasis?
Chronic systemic autoimmune inflammatory skin disease
What are the causes of psoriasis?
Multifactorial - not fully understood:
- Genetics - associated HLAB13/B17/Cw6
- Environmental triggers - skin trauma, stress, infection
- Immunological - abnormal T cell activity
What is the pathophysiology?
- Epidermal hyper-proliferation
- Abnormal keratinocyte differentiation
- Lymphocyte inflammatory infiltrate
What are the peak ages of onset?
16-22yrs
50s
What is the most common subtype of psoriasis?
Plaque psoriasis
What are the dermatological changes seen in psoriasis?
- Symmetrical well-defined red plaques w silvery scales
extensor aspects of elbows, knees scalp and sacrum - Flexures affected but non-scaly
What nail changes are seen?
- Pitting
- Onycholysis - separation from nail bed
- Thickening and subungual hyperkeratosis
How does compllar psoriasis present?
- Generalised - rapid widespread erythema + systemic illness e.g. fever, malaise
- Localised - lesions on palms and soles, yellow + brown pustules on plaques
How does erythrodermic psoriasis present?
Severe systemic upset - generalised redness of the skin
Occurs in known worsening or unstable psoriasis
What is auspitz sign?
Pinpoint bleeding on scale removal
What is koebner phenomenon?
Development of new psoriatic lesions at the site of minor skin injury
How can psoriasis manifest as a seronegative arthropathy?
- mono/oligoarthritis
- psoriatic spondylitis
- asymmetrical polyarthritis
- arthritis mutilans
- rheumatoid like polyarthritis
How does guttate psoriasis present?
- Small scattered round scaly papule affecting trunk and proximal limbs
- Usually after acute strep URTI
How can you diagnose psoriasis?
Clinically but can also do histology
What are possible triggers of psoriasis?
Stress Inf (esp. streps) Skin trauma Drugs (lithium, NSAIDs, BBs, antimalarials) Alcohol Obesity Smoking Climate
What is the topical treatment of psoriasis affecting trunk and limbs?
- Potent CS OD + vit D or vit D analogue OD for up to 4 weeks
- No clearance after max of 8 weeks - vit D/analogue BD
- Potent CS BD or coal tar prep
How much time should you leave between trying 2 diff CS?
4 weeks
Give some examples of vit D analogues
Calcipotriol, calcitriol
how do vit D analogues work?
Reducing cell division and differentiation
They reduce scale and thickness of plaques
can vit d analogues be used long term?
Yes
are vit d analogues safe to use in pregnancy?
No
what is used to treat scalp psoriasis?
Potent topical CS 4 weeks
What are options for treatment of psoriasis in secondary care?
Phototherapy - narrow band UV B light 3x a week
Systemic therapy: methotrexate, ciclosporin, systemic retinoids, biologics
What are the adverse effects of phototherapy?
skin ageing
SCC
