Angioedema
Angioedema is self-limited, non-pitting swelling of the deep dermis and submucosa that follows one of two mechanisms: mast cell (histamine) mediated, which occurs with urticaria and responds to epinephrine and antihistamines, or bradykinin mediated, which occurs without urticaria and does not. Distinguishing the two determines whether treatment is allergic therapy or bradykinin-targeted therapy, and airway involvement is the central danger.
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What this article covers
- Overview
Definition: angioedema is self-limited, non-pitting swelling of the deep dermis, subcutaneous tissue, and submucosa, favoring the face, lips, tongue, larynx, bowel, and genitalia.
- Epidemiology
Histaminergic predominates: most acute angioedema is mast cell mediated and accompanies urticaria, often allergic or idiopathic.
- Risk factors
ACE inhibitor use: the leading drug cause of bradykinin-mediated angioedema; risk persists for months to years of use.
- Pathophysiology
Histaminergic pathway: allergen- or trigger-induced mast cell degranulation releases histamine, increasing vascular permeability in the deep dermis; it accompanies urticaria and often anaphylaxis.
- Clinical features
Non-pitting asymmetric swelling: of the lips, face, tongue, periorbital tissue, extremities, or genitalia, developing over minutes to hours.
- Differential diagnosis
Anaphylaxis: angioedema plus systemic involvement (respiratory compromise, hypotension) after an allergen, unlike isolated angioedema which lacks such systemic features (Anaphylaxis).
- Diagnosis
Classify by mechanism first, because it dictates treatment: angioedema is a clinical diagnosis, and the pivotal distinction is histaminergic (occurs with urticaria and/or anaphylaxis, responds to…
- Management
First, protect the airway (the initial priority): assess for laryngeal involvement and intubate early (or obtain a surgical airway) when there is stridor or progressive tongue and pharyngeal swelling, because deterioration can be rapid.
- Complications
Airway obstruction and asphyxiation: the principal cause of death, from laryngeal edema.
- Prognosis
Histaminergic angioedema: resolves promptly with allergic therapy and trigger avoidance, with an excellent outlook.
- Prevention
Never rechallenge with an ACE inhibitor after ACE inhibitor angioedema, and avoid the class entirely.
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Related articles
- Anaphylaxis
Anaphylaxis is an acute, potentially fatal systemic hypersensitivity reaction from massive mast cell and basophil mediator release, presenting within minutes as skin, respiratory, cardiovascular, and gastrointestinal involvement after allergen exposure. It is a clinical, treat-first diagnosis, and intramuscular epinephrine is the immediate life-saving therapy.
- Urticaria
Urticaria is transient, pruritic, edematous wheals from mast cell histamine release, classified by duration into acute (under 6 weeks) and chronic (6 weeks or longer, usually spontaneous/idiopathic). Diagnosis is clinical with minimal testing, and treatment is stepwise second-generation H1 antihistamines up-titrated as needed, adding omalizumab for refractory chronic disease.