Urticaria

Basics

Description

  • Common presentation, lifetime prevalence 20%
  • More common in females, children, and young adults
  • More common in the atopic patient
  • 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:
    • 40% of urticaria will have a component of angioedema with deeper subdermal or mucosal involvement

Pediatric Considerations

  • Urticaria is often the result of viral infections (especially URIs) and occasionally a reaction to food or drug
  • Swelling of distal extremities and acrocyanosis may be prominent findings in infants
  • Bullae may form in the center of the wheal, especially on legs and buttocks

Etiology

Acute—Course Up To 6 Wk

  • Presumptive trigger may be found, but majority of cases are idiopathic
  • May be secondary to occult or subclinical infection or systemic disease, especially after the emergence of SARS-CoV-2 disease and subsequent vaccination. Up to 2/3 of pediatric cases are eventually found to have positive viral testing to a wide variety of viral pathogens
  • May be manifestation of auto-immune disease spectrum or immune complex induced as well, especially in the chronic urticarial presentation

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