Highlights
- Understanding angioedema's types is crucial for effective treatment and improved patient outcomes.
- Timely recognition and intervention can prevent life-threatening complications from angioedema.
Overview and Definition
Angioedema is sudden, localized swelling of the deeper skin and mucous membranes, often affecting the face, lips, tongue, extremities, airway, and gastrointestinal tract. It results from increased vascular permeability causing fluid accumulation and can range from mild discomfort to life-threatening airway obstruction. It is classified mainly into histamine-mediated (allergic, often with urticaria) and bradykinin-mediated types (including hereditary and acquired angioedema), with distinct causes and treatment responses.
Types and Causes
Mast cell–mediated angioedema, accounting for over 90% of acute cases, involves allergic reactions triggered by allergens like foods, medications, or insect stings, and responds to antihistamines and corticosteroids. Bradykinin-mediated angioedema results from dysregulation of the kallikrein-kinin system, leading to swelling without itching or urticaria and unresponsive to typical allergy treatments. This includes hereditary angioedema (HAE) caused by C1 inhibitor deficiency or dysfunction, acquired angioedema linked to autoimmune or malignant conditions, drug-induced forms (notably ACE inhibitor-related), and idiopathic cases.
Symptoms
Symptoms include sudden, non-pitting, asymmetrical swelling primarily on the face, lips, tongue, extremities, and sometimes the gastrointestinal tract, causing pain or discomfort but usually no itching in bradykinin-mediated cases. Gastrointestinal involvement can mimic acute abdomen with abdominal pain and nausea. Upper airway swelling can cause respiratory distress and airway obstruction, posing an emergency. Allergic angioedema typically presents rapidly with itching and hives, while HAE episodes may have prodromal signs like fatigue and muscle pain.
Diagnosis
Diagnosis involves clinical evaluation of swelling patterns, history, and exclusion of mimics such as cellulitis, contact dermatitis, and other inflammatory or infectious conditions. Laboratory tests, including complement levels (C4, C1-INH) and mast cell tryptase, help differentiate hereditary, acquired, and allergic forms. Airway assessment is critical in suspected laryngeal involvement, sometimes requiring nasopharyngeal laryngoscopy.
Pathophysiology
Histamine-mediated angioedema is caused by mast cell activation releasing histamine, leading to vasodilation, increased permeability, urticaria, and itching. Bradykinin-mediated angioedema involves elevated bradykinin causing vascular permeability and swelling without urticaria or pruritus. Triggers include trauma, stress, medications, and genetic defects affecting C1 inhibitor function.
Treatment and Management
Acute management prioritizes airway protection. Histamine-mediated angioedema responds to allergen avoidance, antihistamines, corticosteroids, and epinephrine in severe cases. Bradykinin-mediated forms, including HAE, require targeted therapies such as C1 esterase inhibitor concentrate, ecallantide, or icatibant; standard allergy medications are ineffective. Long-term management involves prophylaxis to reduce attack frequency and severity, self-administration training, and avoidance of triggers like ACE inhibitors and stress. Supportive care includes pain relief and monitoring.
Complications and Prognosis
Airway obstruction from laryngeal swelling is the most serious complication, requiring urgent intervention. Anaphylaxis may accompany allergic angioedema, complicating treatment. Most episodes resolve spontaneously, but bradykinin-mediated angioedema often requires specialized management. Prognosis improves with accurate diagnosis, appropriate acute treatment, and prophylaxis, especially in hereditary cases.
Prevention
Prevention focuses on identifying and avoiding triggers such as specific drugs, allergens, stress, and extreme temperatures. Patients with hereditary angioedema benefit from prophylactic therapies and education on emergency treatment. Ongoing vigilance is needed for delayed drug-induced angioedema due to medications like ACE inhibitors.
The content is provided by Jordan Fields, Scopewires
