Psoriasis Flashcards
Describe the appearance of Psoriasis?
Numerous small sharply demarcated erythematous papules/plaques with a micaeceous scale
Describe the appearance of Psoriasis in english?
Raised red clean-edged lesions with a sparkly scale.
How does psoriasis affect the nails?
Psoriasis of the nails presents with:
- Onycholysis
- Pitting
- Oil spots
What are koebner’s phenonmenon and Woronoff’s Ring?
Koebnor’s Phenomenon - Lesions appear directly at sites of injury on the skin
Woronoff’s Ring - A blanched halo around lesions following topical therapy
Describe how Psoriasis biopsies appear histologically?
- Hyperkeratosis (Thickened stratum corneum)
- Munro’s Microabscesses (Neutrophils in S. Corneum)
- Psoriasiform Hyperplasia (Thick squamous cell layer, aka Acanthosis)
- Dilated dermal capillaries
- T cell infiltration
Whats the DDX for Psoriasis?
Seborrhoeic Dermatitis
Lichen Planus
Mycosis Fungoides
Describe the aetiology of Psoriasis?
A mixture of genetic susceptibility and an environmental trigger
What genes determine Psoriasis susceptibility?
PSORS1-9 genes
What are the main environmental triggers for Psoriasis?
Infection
Drugs
Trauma
Sunlight
Age of onset is determined by a seperate gene?
HLA-Cw6
When do most people develop Psoriasis?
Peaks at 20-30 and 50-60
But 75% occur before reaching 40
What are the parts of Psoriasis’ pathogenesis?
Stressed Keratinocytes –> Th activation
Interleukins/TNF-alpha stimulate keratinocyte proliferation
Excess VEGF –> Angiogenesis
Neutrophils gather in acute disease causing pustules
Cell cycle is reduced from 28-5 days
How do stressed keratinocytes leads to Th cell activation and what is the consequence?
Keratinocytes activate Dermal Dendritic Cells (dDC)
dDCs trigger lymph nodes to present uncertain antigen to naive T cells
T cells differentiate to Th1, 17 & 22
Th cells cause the plaque formation
How is keratinocyte proliferation stimulated?
Interleukins and Anti-TNFalpha amplify the inflammatory cascade
What are the risk factors for Psoriasis?
FH Peak ages (20-30/50-60) Smoking Alcohol CVD Depression Drug/Light therapies Skin cancer Metabolic syndrome
What are the systemic signs of Psoriasis?
Psoriatic Arthritis
Psychosocial problems
Metabolic syndrome
How is Psoriasis diagnosed?
CLinically
But if atypical take a biopsy and diagnose histologically
How would you treat Psoriasis in the GP?
Soap Substitutes
Emollients
Coal Tar Creams
Vit D3 analogues Topical Steroids (Genitals/flexures) Salicylic acid (keratolytic)
How do Vit D3 analogues help Psoriasis?
They inhibit epidermal proliferation
How would a dermatologist treat Psoriasis?
Crude Coal Tar (Day or inpatient treatment)
Dithranol
UVB phototherapy (for Guttate)
What are the systemic treatments for Psoriasis?
Retinoids
Immunosuppression
Biologics
Describe retinoid use in Psoriasis?
E.g. Acitretin
You must monitor LFTs, lipids and educate that they’re teratogenic for up to 3 yrs post treatment
Describe immunosuppresion use in Psoriasis?
Cyclosporin - Fast acting so good for initial treatment (risks renal damage)
Methotrexate - Good for Psoriatic Arthritis but risks marrow suppression and liver damage
Describe biologic use in Psoriasis?
Anti-TNF e.g. Infliximab
ILK-12, 23 e.g. Ustekinumab
Patients can develop antibodies to these therapies
