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’
What are some risk factors for psoriasis?
- genetic
- infection
- local trauma
- medications
How is psoriasis usually diagnosed?
Clinical diagnosis
What do we do if clinical diagnosis is in doubt for psoriasis?
Skin biopsy:
- intra-epidermal spongiform pustules
- Munro neutrophilic microabscess within the stratum corneum
What does XR show in psoriatic arthritis? (3)
- pencil-in-cup deformity
- new bone forming yet also erosive changes
- periostitis
What is the Koebner phenomenon in psoriasis?
Skin lesions developing at sites of trauma/scars
What is the Auspitz sign (plaque psoriasis)?
Small pinpoint bleeding when scales are scraped off
What are some differential diagnoses for psoriasis? (12)
- eczema (less well-defined border)
- pityriasis rosea (Christmas tree-shaped distribution)
- seborrhoeic dermatitis (scaly eruptions of scalp, eyebrows, paranasal, ears, chest)
- onychomycosis
- mycoosis fungoides
- tinea corporis
- nappy dermatitis
- SCC/actinic keratosis
- lichen planus
- lichen simplex chronicus
- subcorneal pustular dermatosis
- keratoderma blennorrhagicum (reactive arthritis)
What is 1st line for mild plaque psoriasis?
Topical potent corticosteroid (betamethasone, hydrocortisone) PLUS topical vitamin D analogue (calcipotriol)
- corticosteroids reduce inflammation
- vitamin D reduces keratinocyte proliferation
Describe the management plan for mild plaque psoriasis.
- topical potent corticosteroid + topical vitamin D analogue (calcipotriol)
- if no improvement after 8 weeks: vitamin D analogue 2x daily
- if no improvement after 8-12 weeks: potent corticosteroid 2x daily + coal tar preparation
- moderate/severe: phototherapy (UVB), photochemotherapy (PUVA)
What is the difference in steroid use between plaque and flexural psoriasis?
Use milder topical steroids for flexural, because skin is thinner and more sensitive to steroids in flexural regions
Why do we avoid steroid use for >8 weeks in psoriasis?
Skin atrophy, rebound symptoms and striae (Cushing’s)
How do we manage moderate-severe plaque psoriasis?
Phototherapy (UVB) - narrowband UVB light
Photochemotherapy (PUVA)
How do we manage guttate psoriasis?
Phototherapy (topical Rx if lesions are symptomatic)
2nd line - ciclosporin/methotrexate
3rd line - acitretin
How do we manage pustular psoriasis?
Supportive care, phototherapy, systemic agents
What systemic therapy can we give for psoriasis?
Oral methotrexate is 1st line - useful in psoriatic arthritis
How do we manage psoriatic arthritis?
NSAIDs and DMARDs (methotrexate) - avoid oral steroids as it can cause flare-up of skin lesions
What are some complications of psoriasis? (5)
- CVD
- psoriatic arthritis (30%)
- depression
- lymphoma
- secondary infection
Describe the prognosis of psoriasis.
- chronic disease with fluctuating course
- long-term control with topical and/or systemic medications necessary for many patients
