Psoriasis Flashcards
What is psoriasis?
Chronic, genetically, immune-mediated inflammatory skin condition
What kind of lesions is psoriasis usually characterised by?
Usually characterised by typically well-defined, scaly plaques
What is the prevalence of psoriasis?
3% of UK population
How does the prevalence of psoriasis compare between males and females?
M:F is equal
In what age group is the peak incidence of psoriasis?
20s and 50s
Is there any genetic factor to psoriasis?
>1/3 have family history
As well as the physical implications of psoriasis, what else must be considered?
Psychological implications
What other diseases is psoriasis linked to?
Is a systemic disease, linked to metabolic syndrome and cardiovascular disease
Describe the appearance of psorasis lesions?
Red scaly plaques, often symmetrical distribution
What causes psoriasis?
Overactivity of the immune system, excessive production of TH1 cytokines including TNF-alpha:
- Vascular proliferation (erythema), increased cell turnover (plaques and scaling)
Excessive production of what causes psoriasis?
TH1 cytokines including TNF-alpha
What is the aetiology of psoriasis?
- Genetics
- Environment
- Infection
- Strep, candida
- Drugs
- Lithium, beta blockers, NSAIDs, steroid withdrawal
- Trauma
- Sunlight
What infections can cause psoriasis?
Strep
Candida
What drugs can cause psoriasis?
Lithium
Beta blockers
NSAIDs
Steroid withdrawal
Explain the pathogenesis of psoriasis?
Epidermal infiltration by activated T cells:
- Increased epidermal cell proliferation and turnover
- Cell cycle reduced from 28 days to 3-5 days
- Capillary angiogenesis
- Excessive production of TH1 cytokines, especially TNF-alpha, which is linked to flares
Often family history, so genetic link
What are some precipitants to psoriasis?
- Trauma
- Infection
- Drugs
- Sunlight
- Stress
- Smoking
- Alcohol
- HIV
What is A?
Epidermis
What is B?
Dermis
What is this histology of?
Skin
Explain the histology of psoriasis?
- Hyperkeratosis (thickening of stratum corneum) with parakeratosis (keratinocytes with nuclei in statum corneum)
- Neutrophils in stratum corneum (munro’s microabscesses)
- Hypogranulosis, no granular layer (needed for barrier function)
- Psoriasiform hyperplasia: acanthosis (thickening of squamous cell layer) with elongated rete ridges
- Dilated dermal capillaries
- Perivascular lymphohistiocystic infiltrate, T cell infiltration