Psoriasis Flashcards
Learn what this is
What is psoriasis?
- Chronic, immune mediated disease
* Sharply demarcated erythematous plaque with micaceous scale
Why does psoriasis develop?
○ Polygenic predisposition + environmental triggers ○ HLA-Cw6 (chromosome 6) ○ PSORS1-9 ○ Infection ○ Drugs ○ Trauma ○ Sunlight
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 → lymph nodes, present uncertain antigen to naïve T cells
○ Differentiation into Th (T helper) 1, 17 &22
○ → psoriatic dermis → plaque formation
○ Interleukins & TNF alpha amplify inflammatory cascade, stimulate keratinocyte proliferation
○ VEGF → 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 microabscesses)
○ Psoriasiform hyperplasia: Acanthosis (thickening of squamous cell layer) with elongated rete ridges
○ Dilated dermal capillaries
○ T cell infiltration
Describe chronic plaque psoriasis
○ Symmetric
○ Extensor surfaces
Describe palmar plantar psoriasis (pustulosis)
○ 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
○ This can be the most resistant to treatment
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
What can happen in scalp psoriasis?
Can lead to alopecia at affected areas
Describe flexural/ inverse psoriasis
○ Less scale
○ Can be triggered or superinfected by localised dermatophyte, candidal or bacterial infection – these are also differential diagnoses
Describe pustular psoriasis
○ Sterile pustules ○ Sometimes systemic symptoms ○ Causes - Pregnancy - Rapid taper/stop steroids - Hypocalcaemia - Infection ○ Overlap with AGEP (pustular drug eruption), however, in AGEP: - Patient is more unstable - Fever - Wide spread eruptions - No history of psoriasis
Describe erythrodermic psoriasis
○ ‘Red Man’ syndrome
○ >80% body surface area involved
How can psoriasis be managed in primary care?
- Emollients
- Creams vs Ointments
- Soap substitutes
- Vitamin D3 analogues: inhibit epidermal proliferation
- Coal Tar creams
- Topical Steroid – with care. Flexures, genitalia
- Salicylic acid (keratolytic)
How can psoriasis be managed in secondary care?
- Dermatology Referral
- Crude Coal Tar (inpatient or day treatment)
- Dithranol: since 1916. Can burn.
- UVB Phototherapy (not the same as sunbed)
□ Guttate
What are the systemic treatments of psoriasis?
- Retinoid - Acitretin □ Teratogenic, LFTs, lipids - Immunosuppression □ Methotrexate □ Can treat Ps Arthritis □ Max improvement 8-12 weeks □ Ciclosporin □ Renal, cancer risk - Biologic Therapies □ Qualifying criteria, cost □ Anti-TNF: Etanercept, infliximab, adalimumab □ IL-12,23: Ustekinumab □ Patient can form antibodies to biologic
What is the management of erythrodermic psoriasis?
- Recognition
- Admit
- FLUID BALANCE
- Bloods / IV access
- Thick greasy ointment emollients
- Systemic or biologic treatment?
- Trigger?
