Urticaria, also known as welts, hives, or wheals, is characterized by the appearance of intensely pruritic erythematous plaques.[1] It appears clinically as pruritic, pale, blanching swellings of the superficial dermis that last for up to 24 hours. Lesions may be small, large, giant, oval, or annular.Images
Urticaria affects 10% to 25% of the population and can occur in any age group.[2] It is a mast-cell-driven disease. The triggering mechanisms for mast-cell activation in urticaria are not well defined but seem to be multiple and diverse.[3]
Urticaria is classified according to duration of symptoms:
Chronic urticaria is classified into 2 subtypes:[3]
- Chronic spontaneous urticaria: spontaneous appearance of wheals, angioedema, or both ≥6 weeks due to known or unknown causes.
- Inducible urticaria, for example delayed pressure urticaria, heat urticaria, solar urticaria, symptomatic dermatographism, vibratory angioedema, aquagenic urticaria, cholinergic urticaria, and contact urticaria.
Urticaria complicated by angioedema
Some people have urticaria that is complicated by angioedema, a swelling of the deeper dermis and tissues (e.g., mucosal surfaces), with laryngeal edema potentially causing respiratory distress and death.[3] Angioedema is commonly associated with urticaria and may occur at any age.[5] It may not necessarily be seen at the first urticarial episode, but risk of angioedema increases with greater exposure to the allergenic substance.[6]
Clinical presentation of angioedema may include nonpitting edema of the subcutaneous tissues involving lips, face, neck and extremities and/or submucosal tissues affecting the oral cavity, larynx and gastrointestinal system.[7] Associated symptoms may also be present. These are dependent on the underlying etiology. Examples include flushing, bronchospasm, abdominal pain, diarrhea and vomiting.[7] Angioedema without urticaria should prompt further evaluation.[1]Image
