Pustules, ulcers and vesicles Flashcards

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1
Q

define pustules

A

small circumscribed pus filled elevation of the epidermis

  • may be centred on hair follicles or interfollicular
  • transient, often seen as crusts, epidermal collarettes or erosion
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2
Q

causes of pustules

A
  • pyoderma most common in dogs (rare in cats)
  • sterile diseases less common in general eg. drug eruptions, pemphigous folaceous (most common in cats), subcorneal pustular dermatosis, sterile eosinophilic pustulosis
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3
Q

Ddx pustules in dogs

A
  • pyoderma (neutrophils and cocci)
  • pemphigus folaceous (neutrophils and free epithelial cells)
  • drug eruption (variable)
  • subcorneal pustular dermatosis (neutrophils but no bacteria)
  • sterile eosinophilic pustulossis (eosinophils)
  • juvenile cellulitits (neutrophils and macrophages)
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4
Q

Approach to pustules in dogs?

A

cytology
> if consistent with pyoderma, tx Abx and reexamine 10-20d
- skin scrap to r/o demodex
> if no response to Abx/cytology not consistnet
- culture and sesitivity for bacteria (suspect resistnace?)
- skin biopsies to dx all sterile pustular diseases

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5
Q

Apporoach to pustules in cats and horses?

A
  • biopsy all cases (v unusual in these spp)

- Abx tx pending results

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6
Q

Ddx crusting in dogs and horses other than pustules?

A
  • dermatophytes (dogs)

- dermatophilis congolensis (horses)

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7
Q

Define ulceration. Causes?

A
  • break in the continuity of the epidermis to expose underlying dermis
  • consequence of self trauma w/ pruritis
  • consequence of disease of epidermis/epidermo-dermal junction (infections/autoimmune/drug reactions/neoplasia)
  • widespread may reflect progression from vesicles (intraepidermal vesicular dermatitides) and bullae (subepidermal vesicular dermatitides), epidermal separation (interface dermatitis) or epithelioptrophic lymphoma
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8
Q

Prognosis of epithelioptrophic lymphoma?

A
  • poor despite tx

- epidermis damaged by invasion of neoplastic lymphocytes

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9
Q

Workup of ulcerative skin disease?

A

Biopsy routinely as may ddx severe and need aggressive tx

  • intact 1* lesions best
  • excisional biopsy across margins of lesions (if you only biopsy the ulcer, pathologist will tell you its an ulcer!)
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10
Q

What are vesicles?

A
  • fluid filled elevations of the skin LESS THAN 1cm in diameter (Bulla if >1cm)
  • transient in haired skin due to thin epidermis
  • histo: intra-epidermal/subepidermal vesicular dermatitis or interface dermatitis
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11
Q

Aetiology of vesicles?

A
  • viral
  • irritant chemicals/burns
  • auto-immune/immune mediated disease
    > NB: FMD notifiable in farm animals causes vesicles
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12
Q

are drug reactions the same as drug side effects?

A

NO drug reactions immune mediated, drug side effects direct result of chemicals

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13
Q

egs. drug reaction presentations

A
  • urticaria and angioedema
  • exfoliative erythroderma (red scaly skin)
  • autoimmune presentation
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14
Q

Dx drug reaction?

A
  • hx drug exposure
  • clinical signs of drug reaction
  • histo
  • r/o other causes
    > do not rechallenge with offedning drug!!!
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15
Q

Tx drug reactions?

A
  • stop offending drug
  • suppotive/symptomatic tx
  • mark in hx to ensure no future administration
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