Psoriasis Flashcards
What is psoriasis?
Chronic immune mediated disease
Sharply demarcated erythematous plaques with micaceous scale
M=F, 20-30 and 50-60 yrs
How is psoriasis a systemic disease?
5-30% develop psoriatic arthritis
Psychological implications
Metabolic syndrome
Describe the pathogenesis of psoriasis
Polygenic predisposition and environmental triggers
35-90% have FH
HLA-Cw6 (chromosome 6)
Psoriasis susceptibility regions - PSORS1-9
Infections, drugs, trauma and sunlight
Describe the pathophysiology of psoriasis
Adaptive immune system - T cells
Stressed keratinocytes
Activation of dermal dendritic cells (dDCs)
dDCs - lymph nodes, present uncertain antigen to naïve T cells
Differentiation into Th1, 17 and 22
This causes psoriasis dermis and plaque formation as more keratinocytes produced
What do interleukins and TNF alpha do?
Amplify inflammatory cascade stimulate keratinocyte proliferation
VEGF - angiogenesis
Neutrophils in acute, active and 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
Psoriasiform hyperplasia - acanthosis (thickening of squamous cell layer) with elongated rete ridges
Dilated dermal capillaries and T cell infiltration
What is included in the examination of a patients skin with psoriasis?
Distribution
Sharply demarcated erythematous papulo-squamous plaques
Pink or purple in light skin and dark down in dark skin
Numerous small and widely disseminated papules and plaques
Erythroderma (red man syndrome) and pustules
What is looked at when examining patient?
Skin, nails, scalp and Koebner phenomenon
Describe chronic plaque psoriasis
Symmetrical and extensor surfaces
Scaly plaques on elbows and/ or knees
Thick scale and large salmon coloured
Describe Guttate psoriasis
Children and adolescents
Can be triggered from viral or bacterial infection - check ASO titre (for strep.)
Acute onset generalised rash - 205mm pink papules with fine scale
Worse on trunk and proximal extremities
What are the results of Guttate psoriasis?
May resolve or may trigger chronic psoriasis in susceptible patients
Describe palmo-plantar psoriasis or pustulosis
Rash on hands and feet - thick, red and scaly with yellowish brown lesions at edges
Smoking is RF
Sterile inflammatory bone lesions
Describe the presentation of scalp psoriasis
Severe dandruff, pink hyperkeratotic plaques at her scalp extending to hairline, neck and forehead
Can also have nail psoriasis
Can lead to alopecia at affected areas
Describe flexural/ inverse psoriasis
Less scale
Bilateral axillary rash, shiny pink to red sharply demarcated plaques with no scale
Can be triggered or superinfected by localised dermatophyte candida or bacterial infection
Describe pustular psoriasis
Acute onset of generalised red, tender patches
Multiple yellow pustules are seen - sterile
Sometime systemic symptoms
Can overlap with AGEP - acute generalised erythematous pustulosis
What are some risk factors for pustular psoriasis?
Pregnancy, rapid taper/ stop of steroids, hyperglycaemia and infection
Describe erythrodermic psoriasis
Red man syndrome - More than 80% of body surface is involved
History of stable chronic plaque psoriasis
Shivery and generally unwell
Erythematous with fine scale
Pyrexia and low blood pressure
How is psoriasis diagnosed?
Clinical and skin biopsy if atypical
What are some differential diagnosis for psoriasis?
Seborrhoeic dermatitis
Lichen planus - sexual forms
Mycosis fungoides
Bowen’s disease, drug eruption, infection, secondary syphilis, contact dermatitis and extramammary pagets
How is psoriasis managed in primary care?
Emollients - creams and ointments
Soap substitutes
Vitamin D3 analogues
Coal Tar creams
Topical steroids - use with care. Flexures and genitalia
Salicylic acid
What is the mechanism of vitamin D3 analogues?
Inhibit epidermal proliferation
What is the treatment used in secondary care for psoriasis?
Optimise topical therapy
Crude coal tar
Dithranol - can burn and not used regularly
UVB phototherapy
Oral retinoids - Acitrectin and Teratogenic
What immunosuppression is used for psoriasis?
Methotrexate - can treat psoriasis arthritis and max improvement is 8-12 weeks
Ciclosporin - fast acting but can cause renal side effects and carcinogenicity
What small molecule is used for treatment of psoriasis?
Otezla - supresses immune system
What biologic therapies are used in treatment of psoriasis?
Anti-TNF - etanercept, infliximab, adalimumab and certolizumab
IL-12,23 - Ustekinumab
IL-17 - secukinumab
IL-23 - tildrakizumab
Patient can form antibodies so may need to switch biologic
What is used for monitoring progress in psoriasis?
Psoriasis area severity index (PASI) - surface area, plaque colour, thickness and scale
Dermatology Life Quality Index (DLQI)
What is the treatment for erythrodermic psoriasis?
Recognition, admit, fluid balance, bloods/ IV access and thick greasy ointment emollients
What is psoriasis associated with?
CVD, smoking, alcohol, metabolic syndrome, depression, suicide, potential harmful light and drug therapies and risks of long term immunosuppression
