Angioedema Definition Angioedema is a localized, transient swelling of the deeper layers of the skin or mucous membranes, typically involving the subcutaneous tissue, submucosa, or mucosa of the gastrointestinal or respiratory tract. It is similar to urticaria but occurs deeper and may not be associated with itching. Swelling often affects lips, tongue, face, extremities, genitalia, and sometimes the airway. Pathophysiology Angioedema can be classified by mediator type: Histamine-mediated (allergic) Triggered by IgE-mediated hypersensitivity. Rapid onset (minutes to hours). Often associated with urticaria and pruritus. Mediated by mast cell and basophil degranulation → histamine release. Bradykinin-mediated Caused by excess bradykinin, leading to increased vascular permeability. No urticaria or pruritus typically. Examples: ACE inhibitor-induced angioedema Usually involves lips, tongue, or face. Can occur anytime during therapy (even years after starting ACE inhibitors). Hereditary angioedema (HAE) C1 esterase inhibitor deficiency or dysfunction (types I and II). Acquired angioedema Often associated with lymphoproliferative disorders.…
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