Psoriasis Flashcards
What is Psoriasis?
Chronic, immune mediated disease
Sharply demarcated erythematous plaques with micaceous scale
Systemic disease:
5-30% develop psoriatic arthritis
Psychosocial implications
Metabolic syndrome
Who does Psoriasis affect?
3% of UK population, M=F
20-30yrs & 50-60yrs.
75% before 40yrs
Psoriasis Pathogenesis
Polygenic predisposition + environmental triggers
35-90% have a family history
HLA-Cw6
(Chromosome 6)
Age of onset Psoriasis susceptibility regions PSORS1-9
Infection
Drugs
Trauma
Sunlight
Psoriasis Genetics
HLA-Cw6
(Chromosome 6)
PSORS1-9
35-90% have a family history
Psoriasis Immune Pathology
Adaptive immune system
T cells
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
Describe the process of keratinocyte proliferation seen in Psoriasis
* cell cycle length *
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 **
Psoriasis Histology
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
Psoriasis Munro’s microabcesses
Neutrophils in stratum corneum
Psoriasiform hyperplasia:
acanthosis (thickening of squamous cell layer) with elongated rete ridges
Histology of capillaries in Psoriasis:
Dilated
Term used to describe - thickening of stratum corneum - in Psoriasis:
Hyperkeratosis
O/E Psorosis
Skin
Distribution!
Sharply demarcated, erythematous, papulosquamous plaques
Pink or purple in light skin, dark brown or hyperpigmented in dark skin
Numerous small, widely disseminated papules & plaques
Erythroderma (>80% BSA)
Pustules
Subtypes of Psoriasis:
54 year old male presents with a 15 year history of scaly plaques on both elbows. Over the last few months the rash has spread to involve large areas of his body.
He has recently lost his job and has been diagnosed with hypertension.
O/E he has large salmon coloured plaques on his arms, legs and back with thick scale.
Chronic Plaque Psoriasis: symmetric, extensor surfaces
15 YEAR HISTORY
Subtypes of Psoriasis:
A 14 year old boy presents with an acute onset of a generalized rash.
O/E he has multiple 2-5 mm pink papules with a fine scale, worse on the trunk and proximal extremities.
His mother says that he had a throat infection 2-3 weeks prior to the rash.
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.
Subtypes of Psoriasis:
A 32 year old lady presents with several months’ history of a rash on her hands and feet. She works as a beautician / masseuse and wants it to be cured.
O/E the skin on the PALMS and SOLES appears thick, scaly and red with YELLOWIS brown LESIONS at the edges.
Palmo-plantar Psoriasis, or 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
YELLOW - PUSTULES
Subtypes of Psoriasis:
27 year old lady presents to your clinic complaining of severe dandruff. She has tried various shampoos with out much effect. She has noticed that the DANDRUFF is spreading onto her face as well.
O/E you see pink hyperkeratotic plaques at her SCALP, extending just beyond the hairline onto her neck and forehead. She has some pitting at her NAILS.
Scalp Psoriasis
Can lead to alopecia at affected areas
&
Nail Psoriasis
Difficult to treat
Subtypes of Psoriasis:
A 36 year old man presents with several months history of a BILATERAL AXILLARY RASH.
He has been treated with topical and oral anti-fungal agents recently without any benefit. Skin scrapings show no growth.
O/E you see shiny pink to red sharply demarcated plaques with NO scale.
Flexural / Inverse PsoriasisLess scaleCan be triggered or superinfected by localised dermatophyte, candidal or bacterial infection – these are also differential diagnoses
A 50 year old lady presents with an acute onset of generalised red, tender patches. On closer inspection of the patches multiple yellow pustules are seen.
Pustular Psoriasis
Sterile pustules, sometimes systemic symptoms
Pregnancy, rapid taper/stop steroids, hypocalcaemia, infection
Overlap with AGEP (pustular drug eruption)
A 67 year old man arrives with a 35 years history of stable chronic plaque psoriasis.
His wife died 8 weeks ago and his psoriasis started to flare. He was prescribed 2 weeks course of oral Prednisolone, which was stopped without tapering. He presents feeling shivery and generally unwell.
O/E More than 80% of his body surface area is erythematous, with fine scale. He is pyrexial and has a low blood pressure.
Erythrodermic psoriasis
‘Red Man’ syndrome
>80% body surface area involved!!!
Diagnostic Investigations - Psoriasis
Clinical
Skin biopsy if atypical
Psoriasis other dy/dx
Seborrhoeic dermatitis
Lichen planus
Mycosis fungoides
Bowens disease, drug eruption, infection, secondary syphillis, contact dermatitis, extramammary Pagets…
Psoriasis Primary Care
Management/treatment
<30% of patients seen in primary care are referred to dermatology
Emollients
Creams vs Ointments
Soap substitutes
Vitamin D3 analogues: inhibit epidermal proliferation
Coal Tar creams
Topical Steroid – with care.
Flexures, genitalia Salicylic acid (keratolytic)
Psoriasis Secondary Care
Management/treatment
Optimise topical therapy
Crude Coal Tar (inpatient or day treatment)
Dithranol: since 1916. Can burn.
UVB Phototherapy
Oral retinoids
Acitretin
Teratogenic
Psoriasis
Immunosuppression, Small Molecules, Biologic Therapies:
Immunosuppression: Methotrexate Can treat psoriatic arthritis Max improvement 8-12 weeks Ciclosporin Fast acting Renal SEs, carcinogenicity
Small Molecules:
Otezla (apremilast)
Biologic Therapies:
Qualifying criteria, cost
Anti-TNF: Etanercept, infliximab, adalimumab, certolizumab
IL-12,23: Ustekinumab
IL-17: Secukinumab, brodalumab, ixekizumab
IL-23: tildrakizumab, guselkumab, risankizumab
Patient can form antibodies
