Psoriasis Flashcards
What is psoriasis?
Chronic inflammatory skin disease characterised by erythematous, circumscribed scaly papules, and plaques caused by hyperproliferation of keratinocytes
(Relapsing clinical course, with symptom-free intervals)
What causes psoriasis?
UNKNOWN
- Genetic, environmental factors and drugs are implicated
- There is an immune response defined by T cells in the dermis, initiating release of cytokines.
- Histology: keratinocytes overproliferate so there is a thicker layer of keratin causing scales to come off the surface (abnormal T cell activity stimulates keratinocyte proliferation)
What are the risk factors for psoriasis?
Psoriasis can be triggered by a number of factors:
- Skin trauma (Koebner phenomenon)
- Infection: Streptococcus, HIV
- Drugs: B-blockers, Anti-malarials, Lithium, Indomethacin/NSAIDs (BALI)
- Withdrawal of steroids
- Stress
- Alcohol + smoking
- Cold/dry weather
Risk factors for developing psoriasis include family history, HIV infection, obesity and smoking.
Summarise the epidemiology of psoriasis
- Affects 1-2% of population
- Peak age of onset: 20 yrs
What are the different types of psoriasis a pt could present with?
- Chronic plaque psoriasis (most common form) → raised inflamed plaque lesions with a superficial silvery-white scaly eruption on the extensor surfaces of the limbs (knees + elbows), scalp and lower back.
- May be exacerbated by beta blockers, ACEi’s, NSAIDs, Lithium
- Relieved by exposure to sun - Flexural Psoriasis → skin is smooth, less scaly plaques. Occurs on skin creases or flexures (ie. groin, armpits).
- Guttate Psoriasis → widespread, erythematous, fine, scaly papules (small water drop-like lesions) on trunk, arms, and legs.
- The lesions often erupt after an upper respiratory infection (frequently triggered by a streptococcal infection - fever and sore throat).
- Tx with phototherapy. - Psoriatic Arthritis → involvement that causes inflammatory damage and deformity.
- Often precedes development of skin lesions.
- HLA-B27 linked condition
- Asymmetrical Polyarthritis → typically affecting hands and feet
- Involves DIP swelling and dactylitis (sausage fingers)
- Pencil-in-cup deformity of DIP joints on x-ray
- Tx with NSAIDs and DMARDs (methotrexate)
- Avoid oral steroids - Generalised/erythrodermic psoriasis- this is rare but serious form characterised by erythroderma and systemic illness.
What are the presenting symptoms of psoriasis?
- Common locations: scalp, elbows, knees, buttocks, genital area, foot soles
- Itching and occasionally tender skin
- Pinpoint bleeding with removing scales (Auspitz phenomenon)
- Skin lesions may develop at sites of trauma/scars (Koebner phenomenon)
What signs of psoriasis can be found on physical examination?
- Skin signs:
- Discoid/Nummular psoriasis - symmetrical, well-demarcated erythematous plaques with silvery scales over extensor surfaces (knee, elbows, scalp, sacrum)
* Flexural psoriasis - less scaly plaques in axilla, groins, perianal and genital skin
* Guttate psoriasis - small drop-like lesions over trunk and limbs
* Palmoplantar psoriasis - erythematous plaques with pustules on palms and soles
* Generalised pustular psoriasis - pustules distributed over limbs and torso - Nail Signs:
o Pitting
o Onycholysis
o Subungual hyperkeratosis – build up of keratosis under nails - Joint Signs - FIVE presentations of psoriatic arthritis
o Asymmetrical oligoarthritis
o Symmetrical polyarthritis
o Distal interphalangeal joint predominance
o Arthritis mutilans
o Psoriatic spondylitis
What investigations are used to diagnose/ monitor psoriasis?
- Skin Biopsy → when clinical diagnosis in doubt
- Koebner Phenomenon → physical stimuli or skin injury leads to skin lesions
- Auspitz Sign → small pinpoint bleeding when scales are scraped off
How is psoriasis managed?
- 1st Line → topical corticosteroid (hydrocortisone) + topical vitamin D analogue (calcipotriol)
2nd: stop the topical corticosteroid, apply topical vitamin D twice daily
3rd: stop the topical vitamin D, apply potent topical corticosteroid twice daily
- Corticosteroids reduce inflammation, Vitamin D reduced keratinocyte proliferation
- Try to avoid steroid use for >8 weeks, as can lead to skin atrophy, rebound symptoms and striae (ie. cushing’s symptoms)
- Aim for a 4 week break in between courses of topical corticosteroids in patients with psoriasis - Phototherapy (secondary care) → narrowband ultraviolet B light
- Systemic Therapy → oral methotrexate is 1st line (particularly useful if associated joint disease)
2nd: Ciclosporin (1st line if rapid disease control needed/palmoplantar pustulosis/are considering conception) - Biologics
Infliximab
What complications may arise from psoriasis?
cardiovascular complications, psoriatic arthritis, depression
What are the side effects of Ciclosporin
The side effects of ciclosporin can be remembered by the 5 H’s: hypertrophy of the gums, hypertrichosis, hypertension, hyperkalaemia and hyperglycaemia (diabetes)
