Lecture 7: Psoriasis Flashcards
what is psoriasis?
psoriasis is a chronic autoimmune disease characterised by well-demarcated, eythematous, scaly plaques.
psoriasis can be triggered by a number of factors
- skin trauma (Koebner phenomenon)
- infection: streptococcus, HIV
- drugs: beta-blockers, anti-malarials, lithium, indomethacin/NSAIDs (BALI)
- withdrawal of steroids
- stress
- alcohol and smoking
- cold/dry weather
what genes can cause a predisposition towards developing psoriasis?
HLA-Cw6 (chromsome 6)
PSORS1-9
in psoriasis, the cell cycle is reduced from 28 days to how many?
3-5
what would a histology slide osf skin with psoriasis show?
- 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
clinical features of chronic plaque psoriasis
- itchy, well-demarcated circular-to-oval bright red/pink elevated lesions (plaques) with overlying white or silvery scale, distributed symmetrically over extensor body surfaces and scalp.
Nail changes:
- nailbed pitting
- onycholysis: separation of nail plate from nailbed
- subungual hyperkeratosis: thickening of nailbed
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.
what subtype of psoriasis could this be?
- chronic plaque psoriasis: symmetric, extensor surfaces
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.
what subtype of psoriasis could this be?
- Guttate psoriasis
- usually affects children and adolescents
- can be triggered by viral or bacterial infections
- may resolve or may trigger chronic psoriasis in suceptible individuals
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 yellowish brown lesions at the edges.
what subtype of psoriasis could this be?
palmo-plantar psoriasis, or pustulosis
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.
what type of psoriasis could this be?
scalp/nail 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.
what psoriasis subtype could this be?
flexural/inverse psoriasis > less scale
- can be triggered or superinfected by localised dermatophyte, candidal or bacterial infection
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.
which subtype of psoriasis could this be?
erythrodermic psoriasis
- ‘red man’ syndrome
- > 80% body surface area involved
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.
what subtype of psoriasis could this be?
pustular psoriasis
- sterile pustules, sometimes systemic symptoms
psoriasis differential diagnoses
- seborrhoeic dermatitis
- lichen planus
- mycosis fungoides
- etc,…
what is the management of psoriasis in a primary care setting?
- emollients: creams vs ointments
- soap substitutes
- vitamin D3 analogues: inhibit epidermal proliferation
- coal tar creams
- topical steroid
- salicylic acid (keratolytic)
