Excerpt from Angioedema

Synonyms, Key Words, and Related Terms: anaphylaxis, allergies, allergic reaction, urticaria, edema, tongue swelling, angioneurotic edema, atrophedema, Bannister disease, Bannister's disease, circumscribed edema, giant hives, giant urticaria, urticaria gigans, urticaria gigantea, Milton disease, Milton's disease, periodic edema, Quincke disease, Quincke's disease, Quincke edema, Quincke's edema, urticaria tuberosa, dysphonia, dysphagia, respiratory distress, complete airway obstruction, giant wheals, allergic angioedema, idiopathic angioedema, urticarial eruptions, hymenoptera envenomations, food allergies, chronic urticaria, emotional stress, Helicobacter pylori, thyroid autoimmunity, leukemia, arthralgias, palpable purpura

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Background

Angioedema and urticaria should be viewed as varying manifestations of the same pathologic process. Postcapillary venule inflammation results in fluid leakage and edema in both conditions. However, angioedema involves vessels in the layers of the skin below the dermis, while urticaria is localized superficial to the dermis. This results in varying clinical presentations.

The subdermal source of angioedema results in well-demarcated, localized, nonpitting edema. Urticaria is localized to the superficial portion of the dermis and is characterized by well-circumscribed wheals with raised erythematous borders and central blanching. These often coalesce to become giant wheals.

These conditions can occur together or separately. Recurrent episodes of one or both conditions for less than a 6-week duration are considered acute, whereas longer-lasting attacks are considered chronic.

Angioedema, with or without urticaria, is classified as allergic, hereditary, or idiopathic. Complications range from dysphonia or dysphagia to respiratory distress, complete airway obstruction, and death.

Pathophysiology

Angioedema involves vascular leakage beneath the dermis and subcutis. This response is mediated by vasoactive mediators, such as histamine, serotonin, and kinins (eg, bradykinins), which cause the arterioles to dilate while inducing a brief episode of vascular leakage in the venules, where the junction between the endothelial cells appears looser than in the capillaries and arterioles.

Frequency

United States

Approximately 15% of the general population is affected by recurrent idiopathic episodes. The most common kind does not have a discoverable cause.

Mortality/Morbidity

Morbidity and mortality are directly related to the severity of airway obstruction.

Race

No specific racial predilection exists.

Sex

Women tend to have more occurrences than men.

Age

Persons who are predisposed have an increase in frequency of attacks after adolescence, with the peak incidence occurring in the third decade of life.

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