Flashcards in Allergy and the skin Deck (43):
What is hypersensitivity?
An exaggerated immune response which causes damaged to oneself
How can hypersensitivity be classified?
Type 1 - IgE mediated
Type 2 - IgG mediated cytotoxic
Type 3 - Immune complex mediated
Type 4 - Delayed cell mediated
What are allergic reactions?
Immune system response to a normally harmless substance
What is an allergen?
Substance which causes an immune reaction
What is the theory behind the increasing prevalence of allergy?
What is the time frame of a type 1 allergic reaction?
Between minutes to two hours
What routes of exposure can cause a type 1 allergic reaction?
What is the main history feature of a type 1 allergic reaction?
Consistent reaction every time
What are the common ingested allergens?
What are the common inhaled allergens?
House dust mite
What are the common skin contact allergens?
What are the common injected allergens?
How does a type 1 allergic reaction present?
How does urticaria present?
Lasts 2-6 hours but less than 24 hours
What is angioedema?
Swelling of the subcutaneous tissues or mucous membranes
How does angioedema present?
What is anaphylaxis?
Life threatening general or systemic hypersensitivity reaction
How does anaphylaxis present?
Associated skin/mucosal changes
How is suspected type 1 hypersensitivity investigated?
Specific IgE (RAST)
Challenge test (rare)
Serum mast cell tryptase (during anaphylaxis)
What are the benefits and drawbacks of skin prick testing?
Small anaphylaxis risk
When would challenge testing be undertaken?
Skin prick testing negative
How is type 1 allergy managed?
Adrenaline autoinjector (anaphylaxis)
What is the dose of an adrenaline autoinjector in children and adults?
How many adrenaline autoinjector pens should a patient have at the one time?
Is coeliac an allergic condition?
Is lactose intolerance an allergic condition?
What is the timeframe for a type 4 hypersensitivity reaction?
Reaction occurs within 24-48 hours of exposure
Is type 4 hypersensitivity specific to a particular antigen?
Which type of cells are involved in type 4 hypersensitivity?
What type of skin reaction is mediated by type 4 hypersensitivity?
Allergic contact dermatitis
How do type 4 hypersensitivity skin reactions present?
Specific to allergen contact/exposure site/pattern
Mostly eczematous reaction
How are type 4 hypersensitivity skin reactions investigated?
How is a patch test carried out?
Allergens placed in wells
Wells applied to back and removed after 48 hours
Back is checked at 48 hours and 96 hours
If photo-allergens are suspected two wells must be done one exposed to UV and one not
What are the three main categories of dermatitis?
Is irritant contact dermatitis an immunologically mediated process?
How does irritant contact dermatitis happen?
Skin comes into contact with something which directly irritates, abrades or traumatises it
How does irritant contact dermatitis present?
Depends on the pattern of exposure
Give two examples of irritant contact dermatitis
Lip lick dermatitis
What is atopic eczema associated with?
How is atopic eczema distributed?
How is psorisasis distributed?
How is irritant dermatitis managed?
Avoidance or modification