• Cutaneous mast and basophil cellular release of inflammatory mediators, primarily histamine:
    • Increased vascular permeability and pruritus
  • Edema of the epidermis as well as the upper and middle dermis:
    • More common in children and young adults
    • More common in women
    • More common in the atopic patient
  • 40% of patients with urticaria will have a component of angioedema:
    • Affects deeper subdermal and/or submucosal sites

Pediatric Considerations
  • Urticaria is often the result of reactions to foods and infections:
    • Especially viral URIs
  • Swelling of distal extremities and acrocyanosis may be prominent in infants
  • Bullae may form in the center of the wheal, especially on legs and buttocks


  • Presumptive trigger may be found, but majority of cases are idiopathic
  • Course of acute urticaria is 6 wk:
    • 75% idiopathic in nature
    • Autoimmune disease spectrum
    • Immune complex–induced
    • Often an unrecognized recurring physical urticaria
    • May be due to occult or subclinical infection or systemic disease

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