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Key Features

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  • 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

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Clinical Findings

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  • 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 and leukocytosis

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