Urticaria & Angioedema

Key Features

• Common dermatologic conditions that occur at some time in up to 25% of the population

• Urticarial lesions are arbitrarily designated as

  • Acute: lasting less than 6 weeks

  • Chronic: lasting more than 6 weeks

• Cause of acute urticaria can be identified in about half of patients and includes

  • Infectious allergens agents, including streptococci, mycoplasmas, hepatitis B virus, and Epstein-Barr virus

  • Allergies to foods, aeroallergens, latex, drugs, or insect venoms

• Acute urticaria can be induced by opiate analgesics, polymyxin B, tubocurarine, and radiocontrast media via direct mast cell activation

• Urticaria and angioedema can also occur following ingestion of aspirin or nonsteroidal anti-inflammatory agents

• Urticaria or angioedema can occur after the administration of blood products or immunoglobulin from immune complex formation with complement activation, vascular alterations, and triggering of mast cells by anaphylatoxins

• Inducible (physical) urticarias

  • Represent a heterogeneous group of disorders in which urticaria or angioedema is triggered by physical stimuli, including pressure, cold, heat, water, or vibrations

  • Dermographism is the most common form of physical urticaria, affecting up to 4% of the population and occurring at skin sites subjected to mechanical stimuli

  • Lesions are usually rapid in onset, with resolution within hours; however, symptoms can recur for months to years

• Chronic spontaneous urticaria

  • Usually not due to allergies and typically cannot be determined

  • Can be associated with autoimmunity (such as autoimmune thyroid disease) or the presence of basophil-activating IgG autoantibodies directed at the high-affinity receptor for IgE or at IgE

Clinical Findings

• Cold-induced urticaria or angioedema

  • Can occur within minutes of exposure to a decreased ambient temperature or as the skin is warmed following direct cold contact

  • Systemic features include headache, wheezing, and syncope

  • Hypotension and collapse can occur if the entire body is cooled, as may occur during swimming

  • Two forms of dominantly inherited cold urticaria have been described

    • Immediate form: known as familial cold urticaria; erythematous macules appear rather than wheals, along with fever, arthralgias, and leukocytosis

    • Delayed form: consists of erythematous, deep swellings that develop 9–18 hours after local cold challenge without immediate lesions

• Solar urticaria

  • Occurs within minutes after exposure to light of appropriate wavelength

  • Pruritus is followed by morbilliform erythema and urticaria

• Cholinergic urticaria

  • Occurs after increases in core body and skin temperatures and typically develops after a warm bath or shower, exercise, or episodes of fever

  • Occasional episodes are triggered by stress or the ingestion of certain foods

  • Eruption appears as small punctate wheals surrounded by extensive areas of erythema

  • Rarely, lesions become confluent and angioedema develops

  • Associated features can include one or more of the following:

    • Headache

    • Syncope

    • Bronchospasm

    • Abdominal pain

    • Vomiting

    • Diarrhea

  • In severe cases, systemic anaphylaxis may develop

• Pressure urticaria or angioedema

  • Red, deep, painful swelling occurs immediately or 4–6 hours after the skin has been exposed to pressure

  • Immediate form is often associated with dermographism

  • Delayed form

    • May be associated with fever, chills, and arthralgias

    • May be accompanied by elevated erythrocyte sedimentation rate ...