Urticaria, commonly referred to as hives, appears as raised, well-circumscribed areas of erythema and edema involving the dermis and epidermis that are very pruritic. It may be acute (<6 wk) or chronic (>6 wk). Urticaria may be confused with a variety of other dermatologic diseases that are similar in appearance and are also pruritic; usually, however, it can be distinguished from these diseases by an experienced clinician.
Signs and symptoms
The physical examination should focus on conditions that might precipitate urticaria or could be potentially life-threatening and include the following:
- Angioedema of the lips, tongue, or larynx.
- Individual urticarial lesions that are painful, long-lasting (>24 h), or ecchymotic or that leave residual hyperpigmentation or ecchymosis upon resolution are suggestive of urticarial vasculitis.
- Scleral icterus, hepatic enlargement, or tenderness
- Pneumonia or bronchospasm
- Cutaneous evidence of bacterial or fungal infection
Physical urticaria is characterized by the following:
- Blanchable, raised, palpable wheals, which can be linear, annular (circular), or arcuate (serpiginous); can occur on any skin area; are usually transient and migratory; and may coalesce rapidly to form large areas of erythematous, raised lesions that blanch with pressure
- Dermographism or dermatographism (urticarial lesions resulting from light scratching)