Urticaria

Question 1

Definition

Answer 1

Superficial swelling of the skin causing a red, raised and itchy rash

Question 2

Acute

Answer 2

< 6 weeks
Aetiology:
- Allergies to food
- Medication (NSAIDS)
- Animals
- Contact with chemicals
- Stinging nettles
- Viral infection
- Dermatographia (rubbing of the school)

Question 3

Chronic

Answer 3

> 6 weeks
Inducible
Triggered by physical stimulus (cold, heat, exercise, water)
Spontaneous; recurrent urticaria that is mainly idiopathic or caused by chronic infection or autoimmune condition

Question 4

Pathophysiology

Answer 4

Release of inflammatory mediators (mast cells and basophils) in the upper dermis.
Both immune (IgE mediated) and non-immune mechanisms lead to the release of histamine and cytokines causing vasodilation in the skin leading to localised swelling and itching. Can co-exist with angioedema and flushing

Question 5

Signs and symptoms

Answer 5

• Erythematous oedematous lesions
• Pruritus
• Swelling of face, tongue, or lips (angioeodema)

Question 6

Diagnosis

Answer 6

Clinical diagnosis
FBC
- eosinophil (high)
- neutrophil (high)
C4 level = first line screening test in cases of angio-oedema without urticaria. Low levels is suggestive of either hereditary or acquired angio-oedema

Question 7

Treatment

Answer 7

Conservative:
- Advice, avoidance of triggers if known, dietary modification, cooling anti-pruritic lotion (CALAMINE)
Pharmacological:
ACUTE
- second generation non-sedating anti-histamines = fexofenadine
- oral prednisolone (Severe)
CHRONIC
- second generation non-sedating anti-histamines = fexofenadine
- H2 agonist (famotidine)
- short course of prednisolone
- LTRA (montelukast)
- Omalizumab (targets IgE) or ciclosporin