Urticaria

Question 1

RANDOM FLASHCARD: What is a macule and papule?

Answer 1

Macule: lesion associated with change in surface colour and no elevation, well-defined. Papule: lesion that is well-circumscribed and elevated.

Question 2

What is urticaria?

Answer 2

AKA welts, hives, wheals, is characterised by appearance of pruritic erythematous plaques.

Question 3

What is the pathophysiology of urticaria?

Answer 3

Histamine release from cutaneous mast cells resulting in pruritis, and vasodilation and oedema from superficial vasculature. Can also be associated with angioedema which involves fluid leakage from deeper blood vessels in the subcutaneous and submucosal layers. Aetiology of histamine release is unknown, apart from in allergic reactions (IgE-mediated Type 1 hypersensitivity).

Question 4

What are the types of urticaria? (x2)

Answer 4

• ACUTE: appearance of spontaneous wheals, angioedema, or both for 6 weeks or less
• CHRONIC: continuous or intermittently persistent for at least 6 weeks

Question 5

What is wheals?

Answer 5

Describes a lesion that is rounded, pale red papule that is characteristically evanescent (meaning disappearing within 24 hours.

Question 6

What are the sub-types of chronic urticaria? (x2)

Answer 6

• CHRONIC SPONTANEOUS URTICARIA: spontaneous appearance
• INDUCIBLE URTICARIA: delayed appearance e.g., from pressure, heat etc.

Question 7

What is the epidemiology of urticaria: Common?

Answer 7

20% suffer with urticaria. Chronic is rare.

Question 8

What is the aetiology of acute urticaria? (x5)

Answer 8

• Allergic reactions e.g., medication, insect bites, food
• Direct non-immunological mast cell activation: some foods, medication, radiocontrast
• Infection: cause in most children with acute urticaria
• Systemic disease: rare; precedes development of systemic diseases such as SLE, rheumatoid arthritis, malignancies
• Physical urticaria: cold/hot temperature, water (aquagenic), pressure-induced, increase in core body temperature, such as with exercise or emotion (cholinergic)

Question 9

What is the aetiology of chronic urticaria? (x5)

Answer 9

• 90% idiopathic
• Physical urticaria
• Infections
• Systemic diseases
• Medications
• Chronic intake of food that causes urticaria e.g., some patients may unknowingly continue to ingest foods containing an antigen (commonly in processed foods)

Question 10

What are the signs and symptoms of urticaria?

Answer 10

• Pruritic, pale, blanching swellings of superficial dermis
• May be associated with burning pain
• Urticaria lesions often move around
• May be associated with angioedema

Question 11

What are the investigations for urticaria?

Answer 11

• Clinical diagnosis
• Patch testing for allergy testing