Psoriasis Flashcards
What is psoriasis?
Psoriasis is a chronic immune mediated disease.
Inflammatory skin condition characterised by clearly defined, red and scaly plaques (thickened skin).
It is classified into several subtypes
What does psoriasis look like?
Sharply demarcated erythematous plaque with micaceous scale
What is the epidemiology of psoriasis?
3% of UK population, M=F
20-30yrs and 50-60 years
75% before 40yrs
What does psoriasis effect?
Systemic disease
- 5-30% develop psoriatic arthritis
- Psychosocial implications
- Metabolic syndrome
Why does psoriasis develop?
Polygenic predisposition + environmental triggers
How does polygenic predisposition play into the development of psoriasis?
35-90% have a family history
- Both parents: 41%
- One parent: 14%
HLA-Cw6 (Chromosome 6) -> age of onset
Psoriasis susceptibility regions PSORS1-9
What environmental triggers can cause psoriasis?
Infection
Drugs
Trauma
Sunlight
What is the pathogenesis of psoriasis?
Keratinocytes are stressed
Dermal dendritic cells are activated by cytokines such as TNF-a and IL
Dermal dendritic cells -> lymph nodes, present uncertain antigen to naive T cells
Differentiation into Th (T helper) 1, 17 and 22 -> psoriatic dermis -> plaque formation
IL and TNF-a amplify inflammatory cascade, stimulate keratinocyte proliferation
VEGF -> angiogenesis
Neutrophils in acute, active, pustular disease
Cell cycle reduced from 28 days to 3-5
What does the pathogenesis of psoriasis cause?
Psoriasis is characterized by an abnormally excessive and rapid growth of the epidermal layer of the skin.
Abnormal production of skin cells (especially during wound repair) and an overabundance of skin cells result from the sequence of pathological events in psoriasis.
Skin cells are replaced every 3–5 days in psoriasis rather than the usual 28–30 days.
Describe the histology of psoriasis
Hyperkeratosis
-Thickening of stratum corneum
Neutrophils in stratum corneum
-Munro’s microabcesses
Psoriasiform hyperplasia: Acanthosis
- Thickening of squamous cell layer
- Elongated rete ridges
Dilated dermal capillaries
T cell infiltration
What should you tackle in a psoriasis history?
- Age and nature of onset
- Distribution
- Effective treatments
- Medical history
- Family history
- Medications
- QOL
How should you examine the patients skin?
- DISTRIBUTION
- Sharply demarcated, erythematous, papulosquamous plaques
- Numerous small, widely disseminated papules and plaques
- Erythroderma (>80% BSA)
- Pustules
What should you see in someone’s nails with psoriasis?
Oncholysis
Pitting
Oil spots
What else should you check/ look out for on examination appart from skin and nails?
Scalp
Koebner phenomenon
Woronoff’s ring
What is the Koebner phenomenon?
The Koebner phenomenon or Köbner phenomenon (pronunciation), also called the “Koebner response” or the “isomorphic response”, attributed to Professor Heinrich Köbner, refers to skin lesions appearing on lines of trauma.
Occurs secondary to scratching in psoriasis
What is Woronoff’s ring?
Skin condition characterized by a blanched halo of approximately uniform width surrounding psoriatic lesions after phototherapy or topical treatments.
Woronoff’s ring is a section of paler-than-normal (hypopigmented) skin which can sometimes be found surrounding a psoriasis plaque, especially those being treated with UV light and/or coal tar.