Updated: 12/13/2019

Urticaria

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Snapshot
  • APhoto45-year-old woman with a history of systemic lupus erythematous presents to her dermatologist’s office with hives. She complains that this is the “worst it’s ever been.” She has been having episodes of itchy rashes on and off for about 6 months now. On physical exam, her entire back is covered with raised, red wheals. Some are annular. The lesions are blanching and intensely pruritic. She denies any difficulty breathing or any GI symptoms. She has a history of childhood asthma and hypothyroidism, currently on levothyroxine. The lesions usually resolve spontaneously, but this episode is particularly pruritic. She is given an anti-histamine.
Introduction
  • Pruritic inflammation of the skin commonly known as “hives
  • Characterized by superficial, localized edema and erythema
  • Epidemiology
    • most frequent dermatologic disorder seen in the emergency room
  • Pathogenesis
    • involving dermis and epidermis
    • mast cell and basophil release of vasoactive substances
      • histamine, bradykinin, and prostaglandins
      • intense pruritus is from histamine in the dermis
    • type I hypersensitivity reaction
  • Timeline
    • acute is < 6 weeks
    • chronic is > 6 weeks
  • Triggers of acute urticaria
    • drugs
    • food
    • viral infection
    • recent illness
    • insect bite
    • emotional stress
    • cold or heat
    • alcohol ingestion
    • pregnancy
    • exposure to other allergens (pet dander, dust, mold, or chemicals)
    • sun
  • Chronic urticarial is usually idiopathic
    • more likely to be associated with autoimmunity
  • Etiology identified in 40-60% of acute cases and 10-20% in chronic cases
  • Many different types of urticarial with wide range of severity
    • IgE-mediated
    • chemical-induced
    • cold-induced
    • autoimmune
Presentation
  • Symptoms
    • history of previous urticaria
    • pruritus
    • lasts a few hours
    • resolves spontaneously
  • Physical exam
    • well-circumscribed erythema and edema on skin
    • blanching, raised, and palpable wheals 
      • linear
      • annular
      • serpiginous
      • can coalesce
    • can occur anywhere on the body
    • dermotographism (urticaria from light scratching)
      • indicates very sensitive skin
    • assess for angioedema of lips
    • assess for mucosal lesions
    • may have neutrophilic vasculitis
      • painful as well as pruritic
      • purpuric and hyperpigmented lesions
      • systemic systoms such as arthralgias and GI symptoms
Evaluation
  • Labs or biopsy not indicated for acute urticaria unless diagnosis is unclear
  • ↑ IgE
  • For chronic or recurrent urticarial
    • test ESR, TSH, and ANA
  • Biopsy of lesion
    • dermal edema
    • lymphatic channel dilation
Differential Diagnosis
  • Hereditary angioedema 
  • Contact dermatitis
  • Multiple insect bites
  • Erythema multiforme
Treatment
  • If known, discontinue offending agent
  • If concern for airway compromise
    • epinephrine
  • Anti-histamines
    • second generation > first generation
      • second generation anti-histamines are less sedating and have negligible anticholinergic effects when compared to first generation anti-histamines
  • For urticarial vasculitis
    • NSAIDs
    • methotrexate
    • colchicine
    • dapsone
Prognosis, Prevention, and Complications
  • Prognosis
    • most resolve spontaneously
  • Prevention
    • avoid known triggers
    • take second generation anti-histamine daily
  • Complications
    • life-threatening angioedema
    • neutrophilic vasculitis
      • associated with arthritis, renal disease, and hypercomplementemia
      • often lasts > 24 hours
 

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(M3.DM.16.41) A 12-year-old female is brought into your office by her mother. She states that the child was recently diagnosed with "strep throat" and was prescribed penicillin for treatment. Over the last day, the child has suddenly developed a rash that is pruritic and erythematous, as seen in Figure A. The child has a history of asthma. On exam, her vitals are within normal limits. There are areas of erythema along with reddish-whitish papules and plaques (mainly located on her extremities). What is the most important intervention for this child? Tested Concept

QID: 102795
FIGURES:
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Continue current drug regimen

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Corticosteroids

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Antihistamines

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Beta-adrenergic agonists

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5

Discontinue current drug regimen and switch to another antibiotic

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M 11 E

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