Psoriasis Flashcards
What is Psoriasis?
Chronic, genetically determined, immune-mediated, inflammatory skin condition, usually characterized by typical well defined, scaly, plaques
Can also involve nails, hair and joints
Describe the clinical features of psoriasis?
- Red scaly plaques
- Often symmetrical distribution
- Chronic plaque
- Flexural
- Acute Guttate
- Scalp
- Palmoplantar
- Nail
- Pustular
- Erythrodermic
What causes psoriasis?
- Overactivity of the immune system
- Excessive production of TH1 Cytokines inc TNF-alpha
- Vascular proliferation (erythema), increased cell turnover (plaques and scaling)
What are precipitants of psoriasis?
- Genetics
- Environmental
- Infection (strep. candida)
- Drugs - Lithium, Beta-blockers, NSAIDS, Steroid withdrawal
- Trauma – Koebner phenomenon (spread with trauma)
- Sunlight (worsens psoriasis in 10% of people)
- Smoking, alcohol and HIV
Describe the pathogenesis of psoriasis
Epidermal infiltration by activated T cells
• Increased epidermal cell proliferation and turnover
• Capillary angiogenesis
• Excess TH1 cytokine esp. TNF-a
Describe the histology in psoriasis
- Hyperkeratosis (thickening of stratum corneum) with parakeratosis (keratinocytes with nuclei in stratum corneum)
- Neutrophils in strat. corneum
- Hypogranulosis - no granular layer (required for barrier function)
- Psoriasiform hyperplasia: acanthosis (thickening of squamous cell layer) with elongated rete ridges
Describe chronic plaque psoriasis
- Scaly plaques on arms, legs and back
- Severe cases with bigger plaques have stronger impact on psycho-social and CVS health
- Commonly managed with topical treatments in primary care setting
Describe Guttate Psoriasis
- Acute onset of generalised eruption
- Papules with fine scale - worse on trunk and proximal extremities
- Commonly post-viral
- Self-limiting
- Responds well to phototherapy
Describe Palmo-plantar Psoriasis
Skin on the palms and soles appears thick, scaly and red with yellowish brown lesions at the edges
Describe scalp psoriasis
Thick hyperkeratotic plaques in the scalp with some pitting of the nails
What is differential diagnosis of scalp psoriasis?
Seborhoeic dermatitis
What are the features of nail psoriasis?
- Pitting
* Onycholysis (holes/indents)
Describe flexural/inverse psoriasis
Shiny pink to red sharply demarcated plaque with no scaling
• Effect areas normally affected by eczema and dermatitis (i.e. armpits)
Describe pustular psoriasis
Acute onset of generalised red, tender patches - multiple yellow pustules
Describe erythrodermic psoriasis
Generalised erythema of the skin with fine scale
• Red Man’ syndrome
• > 90% body surface area involved
• Needs In-patient treatment
