Urticaria

Question 1

Define

Answer 1

itchy, red, blotchy rash resulting from swelling of the superficial part of the skin. Angiooedema occurs when the deep tissues, the lower dermis and subcutaneous tissues are involved and become swollen.

AKA hives

Question 2

Causes

Answer 2

Caused by activation of mast cells in the skin, resulting in the release of histamines

The cytokine release leads to capillary leakage, which causes swelling of the skin and vasodilation –> erythematous appearance

Possible Triggers:

• ACUTE urticaria
• Allergies (foods, bites, stings)
• Viral infections
• Skin contact with chemicals
• Physical stimuli

CHRONIC urticaria

• Chronic spontaneous urticaria - medication, stress, infections
• Autoimmune

Question 3

Epidemiology

Answer 3

15% of general population experience urticaria at some point in life

Acute is much more common than chronic urticaria

Question 4

Symptoms

Answer 4

Central itchy white papule or plaque surrounded by erythematous flare

Lesions vary in size and shape

May be associated with swelling of the soft-tissues of the eyelids, lips and tongue (angiooedema)

Individual lesions are usually transient

Timescales:

• Acute - symptoms develop quickly but normally resolve within 48 hrs
• Chronic - rash persists for > 6 weeks

Question 5

Investigation

Answer 5

Usually clinical

Tests may be required for chronic urticaria (e.g. FBC, ESR/CRP, patch testing, IgE tests)