Urticaria/Angioedema

Differential Overview

❑ Ingestants

❑ Drugs

❑ Inhalants

❑ Hymenoptera venom

❑ Latex sensitivity

❑ Dermatographism

❑ Pressure urticaria

❑ Cholinergic urticaria

❑ Cold urticaria

❑ Solar urticaria

❑ Infection

❑ Urticarial vasculitis

❑ Hereditary angioedema

❑ Mastocytosis

Diagnostic Approach

Urticaria appears as transient, mutable wheals with red raised serpiginous borders and clear centers, which often coalesce. Urticaria is experienced by 10% to 20% of the population at some time. Angioedema is well-demarcated localized edema.

The appearance may be helpful. Gyrate hives (erythema gyratum) are associated with internal malignancy. Hives without pseudopods suggest allergy. Small lesions with erythematous flares suggest cholinergic urticaria. Urticarial lesions unchanged for 24 hours suggest vasculitis, especially if associated with scaling or purpura.

Clinical Findings

Ingestants  Particularly culpable causes are peanuts, nuts, strawberries, shellfish, milk, soy, and eggs. Drugs and chemicals may also be ingested with food, such as penicillin in meat or milk, tartrazine dye in pills, metabisulfites in salad bar food or wine, or yeast in beer.

Drugs  Drugs such as penicillin, aspirin, or NSAIDs may cause urticaria on an allergic basis. Opiates, thiamine, and pilocarpine may cause urticaria via stimulation of histamine release from mast cells. Progesterone-containing oral contraceptives cause cyclic urticaria.

Inhalants  Mold, dust, and pollens are common inhalant causes.

Hymenoptera venom  Stings may cause reactions ranging from intensely local to generalized anaphylaxis, depending upon the individual’s sensitivity.

Latex sensitivity  Urticaria may occur with occupational or surgical exposure, condom use, or blowing up balloons.

Dermatographism  Demonstrated as a linear wheal induced by briskly stroking the skin, it occurs normally in up to 4% of the population.

Pressure urticaria  Urticaria occurs at points of chronic pressure, such as the waist (belt), feet (running), or hands (manual work).

Cholinergic urticaria  These 1 to 2 mm, papular wheals with surrounding erythema appear in response to exercise or a hot bath. They may be associated with parasympathetic symptoms of cramps, diarrhea, headache, or diaphoresis.

Cold urticaria  Induction of urticaria with cold exposure could be benign or a sign of cryoglobulinemia. Occasionally, cold urticaria may progress to vascular collapse in cold water.

Solar urticaria  Urticaria forming in a photodistribution may be a response to a portion of the UV light spectrum or a sign of erythropoietic porphyria.

Infection  Urticaria may be initiated by viral infection, especially with Ebstein-Barr virus or hepatitis B virus. In hepatitis B, it occurs as part of the prodromal phase along with fever and arthralgias. In hepatitis B and C cryoglobulins and hypocomplementemic vasculitis may develop. Bacterial infection (dental abscess, sinusitis, or prostatitis), parasitic infection (strongyloides, ascariasis, trichuriasis, giardiasis, or trichomoniasis), or cutaneous infection (Candida and dermatophytes) can also cause urticaria.

Urticarial vasculitis  Vasculitis lesions last more than 24 hours and have a central petechiae. They burn rather than itch. If associated with arthralgias and cramping abdominal pain, they could reflect occult lupus or a complement deficiency. Similar symptoms may occur with serum sickness or as a hepatitis B prodrome.

Hereditary angioedema  It occurs as recurrent episodes of well-demarcated local edema, especially in the face and upper airway.

Mastocytosis  Recognized by urticaria pigmentosa, pigmented papules that demonstrate Darier sign, wheals that appear with gentle stroking.

Book Source Details

• Book Title: Field Guide to Bedside Diagnosis
• Author(s): David S. Smith
• Year of Publication: 2007
• Copyright Details: Field Guide to Bedside Diagnosis, Copyright © 2007 Lippincott Williams & Wilkins.

Other Book Chapters Related to Weals

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Copyright Details: Field Guide to Bedside Diagnosis, Copyright © 2008 Williams & Wilkins.

More About Causes of Weals

• Back to symptom: Weals: Introduction (review 156 causes)
• Next Book Extract About Weals: Urticaria and angioedema (Handbook of Diseases)
• All Book Extracts: All Online Book Extracts for Weals

More About This Book: Title: Field Guide to Bedside Diagnosis Authors: David S. Smith Publisher: Lippincott Williams & Wilkins Copyright: 2007 ISBN: 0-78178-165-5

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