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Dermatology COPY > Immune-Mediated Skin Disease > Flashcards

Immune-Mediated Skin Disease Flashcards

1
Q

define autoimmune disease

A

specific humoral or cell mediated immune repsonse against autoantigens -> disease

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2
Q

define immune-mediated disease

A

mediated by the immune system - innappropriate inflammation or immune attack where specific humoral or cellular response to SELF AG NOT demonstrated.
- excludes hypersesntivities (even those these are immune mediated technically)

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3
Q

are immune mediated diseases common?

A

no

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4
Q

what type of immune assault leads to vesicles and bullae? what other lesions may be seen associated with these?

A

basement membrane or basal keratinocytes targetted
(epidermis separates from underlying tissue)
- erosions and ulcers more commonly seen as vesicles fragile

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5
Q

egs. of bullous or vesicular disease

A
  • bullous pemphigoid
  • pemphigous vulgaris
    (NB: pempigous folacious = pustular disease)
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6
Q

what is targetted in subepidermal vesicular autoimmune disease?

A
  • basememnt membrane

- accumulation of inflammatory cells (neutrophils, eosinophils) may be seen in conjunction with 1* lesions

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7
Q

where are subepidermal vesicular autoimmune disease lesions commonly seen?

A

mucocutaneous junction, axilla, groin, mucous membranes

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8
Q

Is bullous pemphigoid a single disease?

A

NO! recent molecular studies -> multiple types of subepidermal vesicular dermatitides eg.

  • BP (bullous pemphigoid) dogs, cats, pigs, horses
  • MMP (mucous membrane pemphigoid) dogs, cats
  • EBA (epidermal bullosa acquisita) dogs
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9
Q

what is targetted in pemphigus vulgaris?

A

desmosomes

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10
Q

Ddx subepidermal vesicular autoimmune diseases?

A
  • other ulcerative autoimmune diseases
  • drug reactions
  • epitheliotropic lymphoma
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11
Q

Dx of subepidermal vesicular autoimmune disease?

A
  • hx, cs

- biopsy (cell rich or cell poor subepidermal vesic. dermatitis)

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12
Q

What occours with intraepidermal vesicular dermatitis?

A
  • autoAb to desmosomal adhesion molecules (desmogleins)
  • separation of keratinocyutes (acantholysis)
  • blister/pustule formation
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13
Q

eg. of intraepidermal vesicular dermatitis? What is seen in this condition?

A
  • pemphigus vulgaris
  • suprabasilar clefting (“tombstone” appearance on histo as basal keratinocytes still attached to basement membrane)
  • oral cavity affected in 90% cases
  • mucocutaneous junction, claws, ears, axilla, grouin
  • 2* bacterial infection common
  • fever and depression severe
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14
Q

Dx of pemphigus vulgaris?

A
  • h, cs

- skin biopsy: cupra basilar split, tombstones, FEW inflam cells)

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15
Q

Tx and prognosis of pemphigus vulgaris?

A
  • suppress immune response (See later questinos on general tx principles)
  • prognosis poor, needs agressive tx, difficult to get on top of
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16
Q

Most common pemphigus disease? What type of disease is this?

A
  • pemphigus folaceous

- intraepidermal pustular disease

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17
Q

Which animals are affected by pemphigus folaceous?

A
  • dogs cats horses
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18
Q

Clinical signs of pemphigus folaceous?

A
  • pustules, crusts, scales, hair loss, erosions, epidermal collarettes
  • face (ears first)
  • feet inc foot pads
  • groin
  • becomes generalised (esp horses)
  • fever and depression if severe
  • may wax and wane with no new lesions for weeks
19
Q

Dx pemphigus folaceous?

A
  • hx, cs
  • biopsy
  • pustule smears (acantholytic cells and neutrophils, NO BACTERIA)
  • histo of multiple intact 1* lesions or edge of recent lesion (less useful)
20
Q

What is the only cause of interface dermatitis?

A
  • AUTOIMMUNE OR IMMUNE MEDIATED DISEASE!!

- > Tx = antiinflam

21
Q

Histo of interface dermatitis? Egs. of pathologies that show this?

A
  • dermo-epidermal junction obscured by inflammatory cells or hydropic [swollen, vacuolated] degeneration (or combination)
    eg.
  • discoid lupus erythematosus (nasal cutaneous lupus)
  • erythema multiforme/toxic epidermal necrolysis (immune mediated often triggered by drugs not autoimmune)
22
Q

Where should melanin be found/not be found?

A

should NOT be found deep to demo-epidermal junction

-> this would be seen as DEPIGEMNTATION of skin

23
Q

Alternative name for discoid lupus erythematosus?

A

nasal cutaneous lupus erythematosus

- not a form of systemic lupus erythematosus

24
Q

nasal cutaneous LE common?

A

uncommon dogs, v rare in cats

25
Q

What may nasal cutaneous lupus erythematosus be exaccerbated by?

A

exposure to sunlight

26
Q

clinical signs of nasal cutaneous lupus erythematosus? breed predisposition?

A

> collies, shelties, gsd, huskies

  • no systemic signs
  • depigmentation, scaling and erythema of the nose (+- ears and periobribatal areas)
  • loss of cobblestone appearance of nasal planum
  • erosion and crusting
  • small oral ulcers
  • histo: cell rich, lymphocytic interface dermatitis
27
Q

Tx discoid lupus erythematosus?

A
  • avoid sunlight
  • initial topical fluorinated GCs BID tapered to EOD
  • switch to less potent 1-2% hydrocortisone or tacrolimus
  • tetracycline/niacinamide tx combination
  • Vit E and EFAs
  • systemic prednisolone +- immunosuppressants if severity ^
28
Q

Tx mild cases of immune mediated/autoimmune disease

A
  • topical steroids
  • vit E
  • oxytet/niacinamide
  • low dose steroids
29
Q

Tx more severe autoimune disease

A

High dose steroid (pred or dexomethosone)
+ azathioprene (NOT CATS) - chlorambucil good for cats
- monitor for myelosuppression fortnightly

30
Q

Dosage prednisolone? Actions?

A
  • fast
    > dogs: 2-4mg/kg SID -> EOD -> taper
    > cats: double dosage required and tolerated
  • lower doses used for allergy tx
31
Q

Dosage azathioprine? Actions?

A
  • combination with systemic presnisolone (first line tx or if pred alone does not work)
  • NOT FOR CATS
    > dogs: 2-4mg/kg/d PO until response seen then EOD for 4-6 weeks -> taper
  • NB. cost
  • monitor myeolosuppression ~ few weeks
32
Q

What alternative drug to azathioprine can be given to cats? Dosage?

A
  • Chlorambucil (good for cats with PF unresponisve to steroids alone)
    > dogs and cats: 0.1-0.2 mg/kg q24-48hrs
  • monitor haem 2x monthly
33
Q

Speed of action ciclopsporin? Efficacy and usefulness?

A
  • works slow
  • $$$
  • poor efficacy in canine PF
    • azathioprine for refrctory cases may be useful
34
Q

What cases is tetracycline and niacinamide indicated for? Dose? When are effects ecpected to be seen?

A
  • Abx + Vit B -> anti-inflam
  • good for mild autoimmune diseases (risks of more potent drugs not justified)
    > dogs>10kg = 500mg each substance q8hrs
    > dogs<10kg 250mg TID
  • expect effects in 8 weeks
35
Q

Is feline cowpox zoonotic? What type of virus is this and which animals acct as reservoir hosts? Which animals are susceptible?

A
  • YES
  • orthopoxvirus
  • voles and woodmice reservoir -> hunting cats esp in rural environment
  • esp seen in autumn when reservoir hosts most active
36
Q

Clinical signs of feline cowpox? Ddx?

A

> Ddx = cat bite abscess/RTA

  • small ulcer/abscessation/cellulitis face or distal limb
  • 7-10d later, (viral replication in raining node and white cell assoc viraemia stage) multiple nodular lesions develop
  • histo: inclusion bodies
  • lesions well demarkated, raised, erthematous, vesicular top -> crust +- central depression or crater
37
Q

Prognosis of pathgenesis of feline cowpox?

A
  • spontaneously resolves after 4-6 weeks

- cats otherwise healthy

38
Q

Dx feilne cowpox?

A
  • virus isolation
  • electron miccroscopy of crusts
  • serology (cats seroconvert early)
  • skin biopsy
    > degernative changes in surface and follicular epithelium inc adnexal glands + marked dermal infiltrate of inflam cells. Characteristic intracytoplasmic eosinophilic inclusion bodies in non-necrotic epidermis
39
Q

Tx feline cowpox?

A

NOT STEROIDS!!! -> pneumonia

  • supportive symptomatic tx
  • cowpox is a zoonosis but standard hygeine measured should prevent spread (beware immunosuppressed people)
40
Q

How is vasculitis characterised?

A
  • many cells in the vessel walls cf. dermis
  • haemorrhage and oedema
  • degeneration of endothelial cells
  • +- infarcts and adnexal atrophy
    > difficult dx in cats and dgos
41
Q

where should inflammatory cells not be seen?

A

near an arteriole

42
Q

Where may vasculitis be seen?

A
  • extremitis (pinna, distal limb)

- immune complex deposition/infectious disease/idiopathic

43
Q

Outline 3 main immune mediated clinical patterns and associated histological patterns.

A

> pustular crusts (PF)
- intraepidermal pustular
- neutrophils and acanthocytes
vesicles and bulla, erosions and ulcers (PV + BP +BP variants)
- intra/subepidermal vesicular, skin and mms
- suprabasalar split (PV), both cell poor
erythema, vesicles, erosions and depigmentation (LE)
- interface, widespread or confined nasal planum
- cell rich, lymphocytic

Dermatology COPY (25 decks)

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