Psoriasis Flashcards
What are the causes of psoriasis?
genetic: HLA-B13 and -B17
autoimmune: abnormal T cell activity stimulates keratinocyte proliferation
environmental: worsened by trauma or stress or triggered by streptococcal infection
What is plaque psoriasis?
The most common subtype
Well demarcated red, scaly patches affecting the extensor surfaces, sacrum and scalp
What is flexural psoriasis?
Psoriasis where the lesions over the skin are not raised and smooth. Found on flexural areas.
What is guttate psoriasis?
Transient psoriatic ‘teardrop’ rash usually preceded by a streptococcal infection.
Most resolve within 3m.
Where does pustular psoriasis most commonly occur?
Palms and soles
What other signs may you see in a patient with psoriasis?
Nail signs: pitting, oncholysis
Arthritis may be seen
What are the complications of psoriasis?
Arthritis (10-40%)
increased incidence of CVD
increased incidence of metabolic syndrome
increased incidence of VTE
What can exacerbate psoriasis?
trauma
alcohol
beta blockers, lithium, hydroxychloroquine, ACEi, NSAIDs
streptococcal infection may trigger guttate psoriasis
What is the management of chronic plaque psoriasis?
1) regular steroid emollient once daily plus a vitamin D analogue once daily for 4 weeks
2) if no improvement = vitamin D analogue twice daily
3) if no improvement after 8-12w = potent corticosteroid applied twice daily for up to 4w.
or dithranol
What are the complications of topical steroid use?
What guidance should be given when prescribing corticosteroids?
skin atrophy, striae and instability of psoriasis
use potent corticosteroids for no longer than 8 weeks
use very potent corticosteroids for no longer than 4 weeks
take 4 week breaks in between courses of steroids
scalp, face and flexures are prone to steroid atrophy so only use topical steroids for 1-2w at a time
How do vitamin D analogues work in psoriasis?
work by reducing cell division and differentiation
erythema remains but the plaque goes
no limits on use and no SE however cannot be used in pregnant women
What is the management of scalp psoriasis?
1) potent topical corticosteroids
2) if no improvement, change formulation (e.g. shampoo or mousse) and/or salicylic acid/emollients
What is the secondary care management of psoriasis?
phototherapy: narrow band UV B light three times a week
PO methotrexate if there is arthritis
What are the features of pityriasis rosea?
herald patch usually on trunk
followed by erythematous, oval, scaly patches which follow a ‘fir tree’ appearance
usually disappears after 4-12w
a common differential is guttate psoriasis
