Psoriasis (DERM) Flashcards
Define psoriasis.
Chronic inflammatory skin disease characterised by erythematous circumscribed scale papules and plaques
Describe the pathophysiology of psoriasis.
Abnormal T cell activity stimulates keratinocyte hyperproliferation –> plaques
Which age groups does psoriasis happen commonly in?
20-40 years old
What are some causes of psoriasis? (4)
- genetic predisposition (60-90% heritability)
- immunology
- infection
- mechanical irritation
What are some triggers for psoriasis / what can exacerbate it? (5)
- trauma
- infection
- medications - BBs, lithium, anti-malarials (chloroquine, hydroxychloroquine), NSAIDs, ACEi, infliximab
- withdrawal of systemic steroids
- alcohol
Describe the clinical course of psoriasis.
Relapsing with symptom-free intervals
What are some different types of psoriasis? (7)
- plaque psoriasis (most common)
- flexural psoriasis AKA inverse psoriasis
- guttate psoriasis
- psoriatic arthritis (30% with psoriasis also have psoriatic arthritis)
- pustular psoriasis (linked to hypoparathyroidism)
- erythrodermic psoriasis
- nail psoriasis
Describe plaque psoriasis (most common).
Raised inflamed plaques with a superficial silvery-white scale eruption
Scale may be scraped away to reveal inflamed and sometimes friable skin
(Auspitz sign - small pinpoint bleeding when scales are scraped off)
What drugs make plaque psoriasis worse? (4)
- beta blockers
- lithium
- NSAIDs
- ACEi
What makes plaque psoriasis better?
Exposure to sun
Describe flexural psoriasis.
Skin is smooth (red) and it occurs on skin creases/flexures (groin, armpits, umbilicus)
Describe guttate psoriasis.
Widespread erythematous fine scaly papules (water-drop appearance) on trunk, arms and legs
When does guttate psoriasis often erupt?
After upper respiratory tract infections - commonly Streptococcal
How do we treat guttate psoriasis?
Phototherapy (topical treatment if lesions are symptomatic)
Describe psoriatic arthritis.
Inflammatory damage and deformity to joints - often proceeds development of skin lesions
30% of patients with psoriasis also have psoriatic arthritis
Which gene is psoriatic arthritis linked to?
HLA-B27
What do we see clinically in psoriatic arthritis?
- asymmetrical polyarthritis of hands and feet
- DIP swelling and dactylitis (sausage fingers)
- pencil-in-cup deformity of DIP joints on XR
How do we treat psoriatic arthritis?
NSAIDs and DMARDs (methotrexate) - avoid oral steroids as it can cause a flare-up of skin lesions
What are two types of pustular psoriasis?
- acute generalised pustular psoriasis (von Zumbusch) is rare, severe and urgent
- palmoplantar pustulosis affects palms and soles and is chronic
Describe erythrodermic psoriasis.
Generalised erythema with fine scaling
Pain, irritation and severe itching
What are some signs of nail psoriasis? (3)
- pitting
- onycholysis (split from nail bed)
- subungual hyperkeratosis
What are some general clinical features of psoriasis?
- skin lesions - erythematous, well-demarcated scaly papules and plaques (purple/silver) on scalp and extensor surfaces of knees and elbows
- joint swelling or pain (psoriatic arthritis in 30%)
- nail changes - pitting, onycholysis, subungual hyperkeratosis
What joint changes are seen in psoriatic arthritis / psoriasis?
- symmetrical polyarthritis (similar to RA)
- asymmetrical oligoarthritis - typically affecting hands and feet (20-30%)
- sacroiliitis / psoriatic spondylitis
- DIP joint disease (10%) e.g. dactylitis (sausage fingers)
- arthritis mutilans - severe deformity fingers/hand, ‘telescoping fingers’
What do the fingers of someone with psoriatic arthritis look like?
Dactylitis - sausage fingers
Arthritis mutilans - ‘telescoping fingers’
