Allergic Skin Disease Flashcards Preview

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Flashcards in Allergic Skin Disease Deck (24)
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1
Q

Define hypersensitivity disease

A

Objectively reproducible signs due to exposure to a defined stimulus at a dose tolerated by normal individuals with NO ALLERGIC IMMUNOLOGIC mechanism or UNKNOWN mechanism

2
Q

Define allergic disease

A

Objectively reproducible signs due to exposure to a defined stimulus at a dose tolerated by normal individuals initiated by IMMUNOLOGIC HYPERSENSITIVITY due to a state of heightened reactivity to antigen or specific immunological mechanisms

3
Q

What is allergic disease?

A

Reaction to a normally innocuous non-self antigen and the allergic inflammation produces a tissue injury and can be induced or aggravated by non-immunological factors

4
Q

What are some examples of hypersensitivity/allergic skin disease?

A
Urticaria/angioedema (syndrome)
'Food allergy'
Contact allergy/dermatitis
Atopic dermatitis
Insect sting/bite hypersensitivities
5
Q

Define utricaria

A
Multiple wheals (hives)
Circumscribed raised lesions caused by dermal oedema
6
Q

Define angioedema

A

Marked localised subcutaneous oedema

7
Q

What is the pathomechanism of urticaria/angioedema?

A

Mast cell is the principle effector cell

Mast cell activation can be IgE dependent (type 1 allergy) or IgE independent (complement activation/non-immunological)

8
Q

What are the clinical characteristics of urticaria/angioedema?

A

Acute, recurrent, chronic, seasonalnon-seasonal, may progress to crusting/sloughing, variable pruritis

9
Q

What are some possible triggers for urticaria/angioedema?

A

Administered/applied substances, infections, parasitis infestation, insect bites/stings, dietary components, aeroallergens, contact allergens, other environmental substances, systemic disease, physical stimuli, hereditary condistion, auto-antibodies, idiopathic

10
Q

How is urticaria/angioedema diagnosed?

A

Avoidance and re-challenge ideally blinded and placebo controlled
For IgE mediated disease demonstration of allergen-specific IgE

11
Q

What are the possible immunological adverse reactions to food?

A

IgE mediated food allergy

Non-IgE mediated food allergy

12
Q

What are the possible non-immunological adverse reactions to food?

A

Idiosyncratic
Pharmacological
Metabolic

13
Q

What are the possible clinical signs of food intolerance and allergy?

A

Gastroenteritis, enteropathy

Urticaria, angioedema, pruritic skin disease

14
Q

How is food hypersensitivity/allergy diagnosed?

A

History and signs, response to restricted diet and relapse on old diet
Intra-dermal and serological tests of no benefit

15
Q

How is food hypersensitivity managed?

A

Allergen avoidance, treat secondary complications, glucocorticoids if allergen avoidance isn’t possible

16
Q

What is the aetiology of atopic dermatitis?

A

Genetics = skin barrier, IgE response, (skin) immune system
Environmental factors = reduced skin barrier, allergen exposure, typre of early immune stimulation (puppy/kitten), other factors?

17
Q

What is the pathophysiology of atopic dermatitis?

A

IMAGE

18
Q

What is the typical history of atopic dermatitis?

A

Age of onset 6mths- 3yrs, pruritis, rashes, ear infections

Time course can be seasonal, non-seasonal, non-seasonal with seasonal exacerbation, intermittent

19
Q

What primary skin lesions are seen with atopic dermatitis?

A

None, erythema, erythematous maculopapular rash

20
Q

What is the distribution of itch and lesions of atopic dermatitis?

A

Ears, face, armpits, feet, ventral abdomen, gluteals and hamstrings
Breed specific distributions

21
Q

What is the pathology of skin and ear disease with atopic dermatitis?

A

Immunological derangement leads to cutaneous abnormalities in skin barrier so Staph pseudintermedius and Malassezia pachydermatis can infect causing skin lesions exacerbating pruritis

22
Q

How is atopic dermatitis diagnosed?

A

Rule out/resolve other pruritic disease
5 of following criteria present = < 3 at onset, mostly indoor, corticosteroid responsive pruritis, chronic/recurrent yeast infections, affected front feet, affected pinnae, non-affected ear margins, non-affected dorso-lumbar area

23
Q

What is the treatment aim of atopic dermatitis?

A

Reduce pruritis to acceptable level with long-term control as safely as possible

24
Q

How is control of atopic dermatitis achieved quickest?

A

Addressing as many trigger factors as possible through combination of treatment modalities requiring a custom-tailored treatment plan