Urticaria

Description

• 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

• 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

Etiology

• 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