Allergy and the Skin

Question 1

What is urticaria?

Answer 1

also known as hives, is an outbreak of swollen, pale red bumps or plaques (wheals) on the skin that appear suddenly – either as a result of the body’s reaction to certain allergens, or for unknown reasons. Hives usually cause itching, but may also burn or sting

Question 2

What is angioedema?

Answer 2

Localised swelling of subcutaneous tissue or mucous membranes
Non pitting oedema
Not itchy (unless associated with urticaria)

Question 3

Describe investigations that can be carried out for allergy

Answer 3

Specific IgE (RAST) – specificity & sensitivity 70-75%
Skin prick or prick-prick testing
Challenge test
Serum mast cell tryptase level (during anaphylaxis)

Question 4

What type of hypersensitivity reaction is allergic contact dermatitis?

Answer 4

Type 4

Question 5

How is irritant contact dermatitis different from allergic contact dermatitis?

Answer 5

It is not caused by allergy. Basically it is caused by the skin coming into contact with agents that abrade, irritate and traumatize the skin directly. It doesn’t not require prior sensitization and like ACD, the pattern also depends on exposure

Question 6

As well as allergy and irritants what other cause of skin rash could you get?

Answer 6

Endogenous- conditions like eczema and psoriasis