Psoriasis Flashcards
(37 cards)
Describe the history of treatment development for psoriasis.
- 1950’s: Steroids
- 1970’s: UVB and methotrexate
- 1980’s: T-cell driven disease
- 1990’s: Vitamin d3 analogues
- 2000’s: Biologics
What is psoriasis?
-Chronic, immune mediated disease characterised by sharply demarcated erythematous plaque with micaceous scale
How many people are affected by psoriasis?
- 3% of UK population, M=F
- 2 peaks occur 20-30yrs & 50-60yrs.
- 75% before 40yrs
How is psoriasis related to systemic disease?
- 5-30% develop psoriatic arthritis
- Psychosocial implications
- Metabolic syndrome
Why does psoriasis develop?
Polygenic predisposition + environmental triggers
What environmental triggers are there for psoriasis?
- Infection
- Drugs
- Trauma
- Sunlight (+/-)
Describe the polygenic predisposition of psoriasis.
- 35-90% have a family history (Both parents: 41%. One parent: 14%.)
- HLA-Cw6 (Chromosome 6) leads to age of onset (indicates type of psoriasis)
- Psoriasis susceptibility regions PSORS1-9
What is the pathogenesis of psoriasis?
-Adaptive immune system (T cells (epidermal: CD8, dermal CD4&8))
-Stressed keratinocytes
Activation of dermal dendritic cells (dDCs) by interleukins, TNF alpha
-dDCs act on lymph nodes, present uncertain antigen to naïve T cells
-Differentiation into Th (T helper) 1,17 and 22
Lead to psoriatic dermis and plaque formation
How is the cell cycle reduced in psoriasis?
- Interleukins & TNF alpha amplify inflammatory cascade, stimulate keratinocyte proliferation
- VEGF leads to angiogenesis
- Neutrophils in acute, active, pustular disease
- Cell cycle reduced from 28 days to 3-5
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) with elongated rete ridges
- Dilated dermal capillaries
- T cell infiltration
What is important when taking the history of someone with psoriasis?
- Age & nature of onset
- Distribution
- Effective treatments
- Medical history
- Family history
- Medications
- Quality Of Life
What may be seen on examination of the patients skin?
- Distribution!
- Sharply demarcated, erythematous, papulosquamous plaques
- Numerous small, widely disseminated papules & plaques
- Erythroderma (>80% BSA)
- Pustules
- Scalp
What may be seen on examination of the patients nails?
- Onycholysis
- Pitting
- Oil spots
Give examples of the subtypes of psoriasis.
- Chronic plaque psoriasis
- Palmo-plantar psoriasis
- Scalp psoriasis
- Nail psoriasis
- Flexural/inverse psoriasis
- Pustular psoriasis
- Erythrodermic psoriasis
Describe chronic plaque psoriasis.
- Symmetric
- Affects extensor surfaces
Describe guttate psoriasis
- Children, adolescents.
- Can be triggered by viral or bacterial infections. Check ASO titre.
- May resolve, or may trigger chronic psoriasis in susceptible individuals.
Describe palmo-plantar psoriasis
- Studies show that psoriasis of the palms and soles tends to have greater impact on QOL compared to more extensive psoriatic involvement not involving the palms and soles.
- Smoking
- Sterile inflammatory bone lesions
Describe scalp psoriasis
Can lead to alopecia at affected areas
Describe nail psoriasis
Difficult to treat
Describe flexural/inverse psoriasis
- Less scale
- Can be triggered or superinfected by localised dermatophyte, candida or bacterial infection (these are also differential diagnoses)
Describe pustular psoriasis
- Sterile pustules, sometimes systemic symptoms
- Can be caused by pregnancy, rapid taper/stop steroids, hypocalcaemia, infection
- Overlap with AGEP (pustular drug eruption)
Describe erythrodermic psoriasis
- Differential Dx ‘Red Man’ syndrome (vancomycin induced drug reaction)
- > 80% body surface area involved
How is a diagnosis of psoriasis made?
- Clinical presentation
- Skin biopsy if atypical
What is the differential diagnosis for psoriasis?
- Seborrhoeic dermatitis
- Lichen planus
- Mycosis fungoides
- Bowen’s disease
- Drug eruption
- Infection
- Secondary syphilis
- Contact dermatitis
- Extra mammary Paget’s
