Psoriasis Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What is psoriasis?

A

a chronic immune mediated disease with sharply demarcated erythematous plaque with scale

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2
Q

why does it develop?

A
  • Polygenic predisposition + environmental triggers
  • 35-90% have a FH
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3
Q

what is the pathogenesis?

A

T-lymphocyte-driven disorder that is a response to an unidentified antigen:

trigger factor –> stressed keratinocytes –> activation of dermal dendritic cells (antigen presenting cells)–> they go to lymph nodes & presents uncertain antigen to naïve T cells –> differentiation to Thelper cells –> psoriasis dermis –> plaque formation

  • interleukins & TNF alpha amplify inflammatory cascade, stimulate keratinocyte proliferation
  • VEGF–> angiogenesis
  • Neutrophils in acute, active, pustular disease
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4
Q

what are trigger factors that can active the antigen presenting cells?

A
  • infections
  • drugs
  • trauma
  • UV light
  • smoking
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5
Q

what’s the histology?

A
  • Hyperkeratosis – thickening of stratum corneum
  • Neutrophils in stratum corneum
  • Acanthosis (thickening of s.basale & s.spinosum) with elongated rete ridges
  • Dilated dermal capillaries
  • T cell infiltrations
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6
Q

on examination, you may see koebner phenomenon. What is this?

A

when lesions develop across injured area

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7
Q

on examination, you may see Woronoff’s ring. What is this?

A

blanched halo of uniform width surrounding psoriatic lesions

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8
Q

Describe chronic plaque psoriasis, and what the plaques look like

A
  • symmetric, extensor surfaces
  • pink–red, well-demarcated plaques, with a silver scale seen especially on extensor surfaces of the knees
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9
Q

Describe guttate psoriasis

  • who does it usually occur in?
  • what can it be triggered by?
  • what is its’ outcome?
A
  • children, adolescents
  • can be triggered by viral or bacterial infections, esp strep throat
  • may resolve or may trigger chronic psoriasis in susceptible individuals
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10
Q

Describe pustular psoriasis

A
  • intense inflammation
  • pustules not infected- are sterile collections of inflammatory cells
  • sometimes systemic symptoms
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11
Q

what are some causes of pustular psoriasis?

A
  • pregnancy
  • rapid taper/stop steroids
  • hypocalcaemia
  • infection
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12
Q

what is a form of pustular psoriasis?

A
  • palmoplantar psoriasis
  • more common in smokers
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13
Q

Describe erythrodermic psoriasis

A
  • ‘red man’ syndrome - >80% body surface area involved
  • may be associated with malaise, pyrexia and circulatory disturbance
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14
Q

what is treatment for erythrodermic psoriasis?

A
  • admit
  • fluid balance
  • bloods / IV access
  • thick greasy ointment emollients
  • if have to give topical steroids, give mildest ones (potent can turn it into pustular)
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15
Q

what does scalp psoriasis look like, and what can it lead to?

A
  • looks like really bad dandruff
  • can lead to alopecia at affected areas
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16
Q

describe nail psoriasis:

-what kind of changes are seen?

A

up to 50% of people with psoriasis experience nail changes:

  • Pitting of nail plate
  • Onycholysis
  • Yellow-brown discolouration
  • Subungual hyperkeratosis
  • Damaged nail matrix and lost nail plate
17
Q

Describe flexural/inverse psoriasis

A
  • Less scale
  • Can be triggered or superinfected by localised dermatophyte, candidal or bacterial infection – these are also differential diagnoses
18
Q

when treating flexural psoriasis, what is usually used?

A

combined cream with steroids & antifungal as there is usually combined fungal infection

19
Q

what are differential diagnoses for psoriasis?

A
  • seborrheic dermatitis
  • lichen planus
  • mycosis fungoides
20
Q

how does seborrheic dermatitis present & what can it be a feature of, if resistant to treatment ?

A
  • presents with erythematous patches with some scales, although patches are more greasy
  • If it is resistant to treatment, can be sign of HIV
21
Q

What is topical treatment for psoriasis?

A
  • Emollients
  • Soap substitutes
  • Vitamin D3 analogues
  • Coal tar creams
  • Topical steroids – with care in flexures, genitalia
  • Salicylic acid (keratolytic)
  • UVB phototherapy
22
Q

how do vitamin D3 analogues act?

A

inhibit epidermal proliferation

23
Q

what is systemic therapy for psoriasis? in order of severity

A
  • Retinoid
  • Immunosuppression – methotrexate, ciclosporin
  • Biologic therapies- anti-TNF ie infliximab
24
Q

who are biologic therapies restricted to?

A

those who have severe disease

25
Q

what are 2 ways to monitor process in psoriasis?

A
  • Psoriasis Area Severity Index (PASI)

–Surface area, plaque colour, thickness, scale

  • Dermatology Life Quality Index (DLQI)

–QOL in last 1 week