Urticaria Flashcards
(48 cards)
What are two other terms used for ‘urticaria’?
1) hives
2) wheels
What is urticaria?
Swelling involving the superficial dermis, raising the epidermis
What is angioedema?
the result of increased vascular permeability that can lead to swelling of the face, tongue, and airway
Summarise the pathophysiology of urticaria:
mast cells release histamine and other pro-inflammatory chemicals which stimulate an inflammatory response
What time frame is used to define acute urticaria?
less than 6 weeks
What time frame is used to define chronic urticaria?
symptoms nearly on a daily basis for 6 weeks
Give 6 causes of acute urticaria:
1) allergies to food, medications or animals
2) contact with chemicals, latex or stinging nettles
3) medications
4) viral infections
5) insect bites
6) dermatographism
What is dermatographism?
rubbing of the skin
Describe the clinical presentation seen in urticaria:
highly pruritic raised skin rash with lesions that may be ring shaped with central raised swelling surrounded by an area of erythema
What is meant when acute urticaria is described as ‘fleeting’?
the raised skin often appears and disappears quickly
What is chronic urticaria?
an autoimmune condition where autoantibodies target mast cells and trigger them to release histamines
What is chronic idiopathic urticaria?
recurrent episodes of chronic urticaria without a clear underlying cause or trigger
What are the 3 types of chronic urticaria?
1) chronic idiopathic urticaria
2) autoimmune urticaria
3) chronic inducible urticaria
Give 6 triggers of chronic inducible urticaria:
1) sunlight
2) temperature change
3) exercise
4) strong emotions
5) hot/ cold weather
6) pressure (dermatographism)
What are pruritic wheels?
Recurrent transient erythematous and oedematous lesions that last less than 24 hrs
How often does angio-oedema occur in urticaria?
40% of urticaria cases
What is physical urticaria caused by?
- Dermographism
- Cold contact
- Delayed pressure
- Solar urticaria
What is urticarial vasculitis?
Cutaneous lesions that resemble urticaria and small-vessel cutaneous vasculitis (Palpable purpura)
If low complement levels, it may be associated with SLE
What type of hypersensitivity reaction is urticaria?
Type 1
What are the risk factors for urticaria?
- Positive family history
- Exposure to drug/food trigger
- Recent viral infection/insect bite
- Female sex
What is found upon history and examination of a patient with urticaria?
- Urticaria lesions (wheals) are reddish or white transient papules or plaques representing dermal oedema
- lesions are widespread and last a few hours
- Lesions may become confluent and form circular or sinusoidal patterns
What are the key diagnostic factors of urticaria?
- Erythematous oedematous lesions
- Pruritus
- Resolutions within 24 hrs
- Swelling of tongue, face and lip
- Blanching lesions
- Stridor (uncommon)
What are 5 differential diagnoses for Urticaria?
- Dermographism
- Atopic dermatitis
- Contact dermatitis
- Urticarial vasculitis
- Papular urticaria (insect bites)