Psoriasis Flashcards
What is the definition of Psoriasis?
A chronic inflammatory skin disease due to hyper-proliferation of keratinocytes and inflammatory cell infiltration
What is the aetiology of Psoriasis?
- Complex interaction between genetic, immunological and environmental factors
- Polygenic Predisposition:
- > 35-90% have a FH
- > PSORS1 on chromosome 6
- Environmental Triggers:
- > infection (ie. tonsillitis)
- > drugs, stress, alcohol
- > trauma - may produce Koebler phenomenon
- > sunlight
What is the pathophysiology of Psoriasis?
Hyperproliferation of the keratinocytes in the epidermis, with an increase in the epidermal cell turnover rate
(reduction of cell cycle: skin usually renewed every 28 days -> sped up to 3-5 days in Psoriasis)
What is the histology of Psoriasis?
- Hyperkeratosis (thickening of the stratum corneum
- Neutrophils in str. corneum (munro’s microabscesses)
- Psoriasiform Hyperplasia: acanthosis (thickening of squamous layer) with elongated rete ridges
- Dilated Dermal capillaries
- T cell infiltration
What is the Clinical Presentation of Psoriasis?
- Skin:
- > Sharply demarcated, erythematous, papulosquamous plaques with micaceous scale
- > itchy, burning or painfu lesions
- > Auspitz sign
- > Distribution: symmetrical, extensor surfaces
- > pink or purple in light skin, dark brown or hyperpigmented (black) in dark skin
- > Erythroderma (>80% BSA)
- > sterile pustules
- Scalp:
- > Alopecia
- Nails:
- > Onycholysis
- > Nail pitting
- > Oil spots
- Systemic:
- > Psoriatic Arthritis
- > Psychosocial implications
- > Metabolic syndrome
- Koebner phenomenon
- > due to trauma (ie. injury after gardening -> psoriasis appears there!)
What are the different types of Psoriasis? (7)
- Chronic Plaque Psoriasis
- Guttate Psoriasis
- Palmo-Plantar Psoriasis / Pustulosis
- Scalp/Nail Psoriasis
- Flexural/Inverse Psoriasis
- Pustular Psoriasis
- Erythrodermic Psoriasis
What are the identifying features of Chronic Plaque Psoriasis?
- symmetric
- extensor surfaces
- > (ie. elbows, knees, sacral areas)
“54 year old male presents with a 15 year history of scaly plaques on both elbows”
What are the identifying features of Guttate Psoriasis?
- Children, adolescents
- Check ASO titre
- > can be triggered by viral or bacterial infection
- May resolve, or may trigger chronic psoriasis in susceptible individuals
“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 are the identifying features of Palmo-Plantar Psoriasis/Pustulosis?
- Greater impact on QoL
- Smoking
- Sterile inflammatory bone lesions
“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 are the identifying features of Scalp/Nail Psoriasis?
- Scalp Psoriasis: can lead to Alopecia
- Nail Psoriasis: onycholisis, nail pitting, oil spots -> difficult to treat
“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 are the identifying features of Flexural/Inverse Psoriasis?
- Less scale
- Can be triggered or super-infected by localised dermatophyte, candidal or bacterial infection (also the differential diagnoses!)
“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 are the identifying features of Pustular Psoriasis?
- Sterile pustules -> sometimes systemic symptoms
- Pregnancy, rapid taper/stop steroids, hypocalcaemia, infection
- Overlap with AGEP (pustular drug reaction)
“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 are the identifying features of Erythrodermic Psoriasis?
- “Red Man” syndrome
- > 80% BSA involved
- systemically unwell
“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. “
How is the diagnosis of Psoriasis made?
- Clinical (!!!)
- Skin biopsy if atypical (rare)
What is the treatment of Psoriasis in primary care?
Localised and mild
- General measures:
- > avoid known precipitating factors
- > emollients to reduce scales
- > soap substitutes
- Topical therapies:
- > Vit D3 analogues -> inhibit epidermal proliferation
- > Topical corticosteroids
- > Keratolytics
- > Coal tar creams
