Urticaria

Urticaria, also known as hives, is a very common clinical presentation characterized by transient (<12 hours), itchy dermal wheals. Angioedema is defined as subcutaneous or mucosal (often of the lips) swelling that is episodic and recurrent; it may occur alone or in association with urticaria. Chronic idiopathic urticaria and/or angioedema in children may be exacerbated during puberty.

Differential Diagnosis

• Idiopathic urticaria without angioedema
  –Most common diagnosis in patients with hives
  –Often related to food or drug allergies, bites, or stings
  –25% of patients with one episode will progress to chronic urticaria

• Chronic urticaria
  –Idiopathic in 50% of cases
  –Chronic idiopathic urticaria spontaneously resolves within 2 years in 80% of patients
  –Criterion for chronic urticaria is duration of more than 6 weeks
• Occult infection (e.g., sinusitis, oral infection, cholecystitis, vaginitis, prostatitis, hepatitis, HIV, tinea manus or pedis)
• Malignancy
• Thyroid disease
• Drugs (e.g., radiocontrast media, penicillin, salicylates, benzoates, azo dyes)
  –May result in life-threatening episodes of urticaria and acute angioedema that can lead to anaphylaxis
• Urticaria secondary to physical stimuli [e.g., exercise (cholinergic), vibratory pressure, sun exposure (solar urticaria), cold exposure]
  –Dermographism occurs in 5% of the population; manifests as a physical urticaria that arises in the distribution line of a scratch or rubbed skin area
• Hereditary or acquired deficiency of complement factor C1
  –Generally appears as episodic angioedema in the absence of urticaria
  –Only in the absence of urticaria should hereditary or acquired complement deficiency be considered

• Angioedema-urticaria-eosinophilia syndrome
  –Associated with elevated serum IgE, fever, and fluid retention during an acute attack
• Urticarial vasculitis
  –Presents as urticaria that lasts longer than 12–24 hours
  –Associated with autoimmune disease (e.g., systemic lupus erythematosus)
• Cutaneous mastocytosis/urticaria pigmentosa

Workup and Diagnosis

• Complete history and physical examination
  –Family history of angioedema, anaphylaxis, etc.
  –Seasonal or activity-related (work/home) symptoms
  –Note whether urticaria occurs after ingestion of certain foods or with physical stimuli (e.g., exercise, pressure)
  –Physical exam should evaluate for underlying occult infections (e.g., UTI, vaginal yeast infection, tinea)
  –Firmly trace the blunt tip of a cotton applicator across the patient's back; patients with dermographism will develop a pruritic urticarial wheal within 5 minutes

• Determine whether the patient has isolated urticaria, urticaria with angioedema, or isolated angioedema
• Consider sinus X-rays, T₄, TSH, and thyroid antibodies
• In isolated angioedema without urticaria, check C2, C4, and/or C1 esterase inhibitor serum levels
• IgE level measurement is indicated if angioedema-urticariaeosinophilia syndrome is suspected
• If urticarial lesions last longer than 12–24 hours, a punch biopsy of the involved skin is indicated to confirm the presence of vasculitis
• Perform age-appropriate malignancy screening
• If a cause cannot be found, consider referral to a dermatologist to rule out an occult etiology, although many cases will ultimately be deemed idiopathic

Treatment

• Identify and avoid physical or drug triggers
• Systemic antihistamines (e.g., hydroxyzine, doxepin, cimetidine) are helpful and may be used alone or in combination with each other or with nonsedating antihistamines (e.g., loratidine, cetirizine, fexofenadine)
• Severe attacks with associated angioedema may require administration of prednisone and epinephrine (consider pen-type epinephrine injector such as Epi-Pen_^R)
• Danazol is used to treat only the rare, hereditary subset of angioedema (without urticaria); it stimulates hepatic production of the dysfunctional or absent C1 esterase inhibitor, thereby normalizing the complement cascade
• Treat yeast, tinea, or bacterial infections of the skin, mucosa, sinuses, or other locations with appropriate antifungal or antibacterial preparations
• Treat thyroid disease if found

Book Source Details

• Book Title: In a Page: Signs and Symptoms
• Author(s): Scott Kahan, Ellen G. Smith
• Year of Publication: 2004
• Copyright Details: In a Page: Signs and Symptoms, Copyright © 2004 Lippincott Williams & Wilkins.

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More About This Book: Title: In a Page: Signs and Symptoms Authors: Scott Kahan, Ellen G. Smith Publisher: Lippincott Williams & Wilkins Copyright: 2004 ISBN: 1-4051-0368-X