Urticaria (Acute, Chronic)

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.

Question 2

Aetiology:

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

Question 3

Triggers of acute urticaria:

Answer 3

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

Question 4

Triggers of chronic urticaria:

Answer 4

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

Question 5

Epidemiology:

Answer 5

• 15% of general population experience urticaria at some point in life
• Acute is much more common than chronic urticaria

Question 6

Symptoms and signs:

Answer 6

• Central itchy white papule or plaque surrounded by erythematous flare
• Blanching, oedematous, non-painful, pruritic
• 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
• Stridor – a high-pitched wheezing sound caused by disrupted airflow

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

Question 7

Investigations:

Answer 7

• Usually clinical

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