Psoriasis Flashcards
Psoriasis - intro
- Bimodal onset - peaks 3rd and 6th decades
- abnormal T cell activation causes keratinocyte proliferation and early migration
- genetic links: HLA CW6, HLA B27 (linked with psoriatic arthritis)
Psoriasis - triggers
- infection: e.g. Strep throat (beta haem strep), HIV
- durgs: e.g. beta blockers, lithium, anti-malarials
- alcohol*
- pregnancy
- stress
- light treatment (used for psoriasis, but in some cases can make it worse)
- trauma to skin (Koebner phenomenon)
*alcohol makes psoriasis worse and contributes to liver abnormalities in pts at risk of NAFLD
Patterns of Psoriasis - Chronic Large Plaque
- erythematous injurated (thick and stiff on palpation) plaques
- thick silvery scales
- very well demarcated (as opposed to eczema)
- locations: extensors, scalp, gluteal cleft, genitalia
Guttate Psoriasis
- raindrop lesion = scaly papules, generally on trunk
- usually younger patients
- commonly preceded by strep throat
- predisposes to plaque psoriasis later in life
- treated with phototherapy
Palmar Plantar Pustulosis
- pustules on sheaths of tense sterile blisters on hands and feet
- resolve and leave brown macules
- almost always a smoking history
Nail Psoriasis
- nail pitting, onycholysis (nail lifts off nailbed), subungual keratosis (thickened keratin underneath nail)
- can also get leukonychia
- predisposes to psoriatic arthritis
Pustular Psoriasis
- patient quite unwell - malaise, fever
- widespread erythema with pustules
- common in hands but can involve whole body
- common trigger is withdrawal of oral steroids* (also infections, hypercalcemia and pregnancy)
*you should not give oral steroids to psoriasis patients (due to risk of it becoming pustular when you withdraw them)
Flexural Psoriasis
- difficult to spot as not typically scaly, but shiny and only slightly raised
- can have fissure in the crease
- can be misdiagnosed as a fungal infection (e.g. tinia), but those are usually unilateral while psoriasis bilateral
Extra-systemic presentations
- IBD
- Psoriatic Arthritis
- Metabolic Syndrome
- Mental Health
- increased CV risk
hence ask about other systems in psoriasis history - esp. MSK and CVS
(Exam question)
Rash following sore throat? - DDx
- Guttate Psoriasis
- Small vessel vasculitis
- Glandular Fever (treated with penicillin)
- Drug Rash
- Pityriasis rosea
Is psoriasis itchy?
It can be itchy, but not a hallmark
- if patient presents with a lot of itching, rule out:
1. scabies
2. dermatitis herpetiformis (coeliac’s)
Psoriatic Arthritis - main features
Psoriatic Arthritis: asymmetrical oligoarthritis - nail changes, fingers/toes (dactylytis), DIP/RA like, Spondylitis/Sacroilitis,
- usually seronegative (-ve RF)
- HLA B27
- PEST score: screening tool for psoriatic arthritis (used to refer patients to rheumatology)
Treatment - overview
- emollients (ointments better than creams)
- topical steroids
- vitamin D3 analogues
- coal tar
- dirthranol
- light treatment
- Immunosuppressants
- Biologics
Vitamin D3 Analogues
- e.g. calcipotriol, calcitriol
- limit use - as they can cause hypercalcaemia
- preparations include vit D3 analogues alone (e.g. dovonex) or combined with topical steroid, e.g. dovabet (contains betnovate - potent steroid)
Other Topical Treatments
Coal Tars (cream, ointment) - smelly and stain skin, can cause skin irritation so use cautiosly on flexures
Dithranol (paste or cream)
- usually as inpatient or day care, as it stains a lot and can also burn skin, so only used on thick plaques (only suitable for large plaque psoriasis)
- can be used with phototherapy
