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KembaraXtra-Medicine- Angioedema
Basic Information
Urticaria and angioedema are mucocutaneous swellings that occur after release of vasoactive mediators. Urticaria affects the superficial dermis and produces wheals, whereas angioedema results from a transient increase in vascular permeability in mucosal/submucosal or dermal/subcutaneous tissues, leading to deeper tissue swelling.
Synonyms
Angioneurotic edema; Hereditary angioedema (HAE).
ICD-10-CM Codes
T78.3 Angioedema; D84.1 Angioedema, hereditary.
Epidemiology and Demographics
Urticaria and angioedema together have an incidence of about 100 to 3000 per 100,000 persons, and approximately 7.4% of the general population will experience angioedema alone. Around 25% of people will have urticaria and/or angioedema at some point in life. Hereditary angioedema occurs in about 1 in 50,000 persons. African Americans have higher rates of ACE inhibitor–induced angioedema. Angioedema occurs more often in women than men and commonly begins after adolescence, often in the third decade of life. Angioedema can occur with urticaria (about 40%) or alone (about 20%); the remaining ~40% have urticaria alone. For HAE due to C1 inhibitor problems, mean onset is 8–12 years and it rarely presents before age 1.
Physical Findings and Clinical Presentation
Angioedema may be acute or chronic. Acute angioedema is defined as symptoms lasting up to 6 weeks, while chronic angioedema lasts longer than 6 weeks. Typical swelling is nonpruritic, nonpitting, burning, and occasionally painful, involving deep skin layers or submucosal membranes. It is poorly demarcated and most often affects eyelids, lips, tongue, and extremities. It can involve the upper airway and cause respiratory distress, and it can involve the gastrointestinal tract, producing cyclic abdominal pain, nausea, vomiting, and diarrhea. Symptoms generally resolve slowly over hours to a few days.
Etiology and Pathophysiology
Angioedema (with or without urticaria) is broadly classified as histaminergic (mast cell–mediated or idiopathic) or bradykinin-mediated (such as hereditary forms). It is primarily triggered by immune activation with mediator release (histamine, serotonin, bradykinin), causing postcapillary venule inflammation, vascular leakage, and edema in deeper dermis/subcutaneous tissues. Mechanisms can be immunologic or nonimmunologic. IgE-mediated angioedema may follow exposure to foods (milk, eggs, peanuts, shellfish) or drugs (beta-lactam antibiotics, aspirin, NSAIDs, phenytoin, sulfonamide antibiotics, recombinant tissue plasminogen activator). Complement/immune-complex–mediated pathways can activate mast cells and may present as serum sickness.
Hereditary angioedema is subdivided into HAE type 1 (C1 inhibitor deficiency), HAE type 2 (C1 inhibitor dysfunction), and HAE with normal C1 inhibitor function (HAE nC1-INH). HAE-1 and HAE-2 are commonly due to autosomal dominant SERPING1 mutations affecting C1 esterase inhibitor (C1-INH). C1-INH inhibits plasma kallikrein; without adequate inhibition, kallikrein promotes bradykinin generation. Bradykinin is a potent vasodilator that increases capillary permeability and activates pain receptors, so excess bradykinin leads to angioedema. HAE-1 and HAE-2 are typically associated with low C4 due to complement activation, because C1 inhibitor is a major regulatory protein in the complement cascade.
Acquired angioedema is often linked to underlying disease—most commonly B-cell lymphoproliferative disorders—or may occur from autoantibodies against C1 inhibitor. Other triggers include infections (herpes simplex, hepatitis B, Coxsackie A/B, Streptococcus, Candida, Ascaris, Strongyloides), insect bites or stings, stress, physical factors (cold, exercise, pressure, vibration), connective tissue diseases (systemic lupus erythematosus, Henoch–Schönlein purpura), and idiopathic causes. ACE inhibitors can increase kinin activity and precipitate angioedema. Other medication triggers include antibiotics (beta-lactams, quinolones), opiates, and muscle relaxants (succinylcholine).
Diagnosis
A careful history and physical examination usually establish the diagnosis. Extensive laboratory testing is often of limited value.
Differential Diagnosis
Consider anaphylaxis, contact dermatitis, cellulitis, lymphedema, arthropod bite, hypothyroidism, atopic dermatitis, mastocytosis, granulomatous cheilitis, bullous pemphigoid, urticaria pigmentosa, erythema multiforme, epiglottitis, peritonsillar abscess, parasitic infection, and superior vena cava syndrome.
Workup
A broad workup to identify a cause is frequently unrevealing (about 40%). Testing is guided by the clinical history and exam. Basic tests such as CBC, ESR, and urinalysis may help in initial evaluation. Serum total tryptase can help confirm mast cell–mediated anaphylaxis. C4 is usually low in acquired and hereditary angioedema that occurs without urticaria; when C4 is low, measure C1-INH level and functional activity. Rarely, HAE may present with normal C4 but reduced C1-INH. If food allergy is suspected, skin prick testing and/or in vitro specific IgE testing (e.g., ImmunoCAP) may be used. Skin biopsy is generally reserved for chronic angioedema that is refractory to corticosteroids. Stool ova and parasite testing may be considered when parasitic infection is a concern.
Treatment: Nonpharmacologic Therapy
Remove or eliminate the offending agent when possible and avoid known triggers such as cold, stress, and culprit medications (especially ACE inhibitors). Cold compresses can be applied to affected areas for symptomatic relief.
Acute General Treatment
Life-threatening angioedema involving the larynx is treated urgently, although it is important to recognize that bradykinin-mediated angioedema responds minimally to these standard allergic-reaction medications. Typical emergency medications include subcutaneous epinephrine 0.3 mg (1:1000), an H1 antihistamine such as diphenhydramine 25–50 mg IV/IM or cetirizine 10 mg (listed as IV in the source), an H2 blocker such as cimetidine 300 mg IV or famotidine 20 mg IV, and methylprednisolone 125 mg IV.
For mast cell–mediated, nonhereditary angioedema, maintenance therapy centers on H1 antihistamines: cetirizine 10 mg daily (sometimes up to 4× FDA-approved dose), fexofenadine 180 mg daily (sometimes up to 4× dose), hydroxyzine 10–25 mg every 6 hours, or diphenhydramine 25–50 mg every 6 hours. H2 antihistamines can be added (cimetidine 400 mg twice daily or famotidine 20 mg twice daily). Doxepin 25–50 mg at bedtime can be used as an adjunct. Corticosteroids may be used for symptomatic relief in refractory acute cases. Antihistamines are ineffective for hereditary angioedema attacks.
Acute HAE attacks due to C1 inhibitor deficiency respond well to targeted therapies. Approved abortive options include plasma-derived C1 inhibitor concentrate (Berinert), icatibant (Firazyr), a bradykinin B2 receptor antagonist, and ecallantide (Kalbitor), a kallikrein inhibitor. Purified plasma-derived C1-INH replacement is considered effective and safe for acute attacks.
Chronic Treatment
Chronic histaminergic angioedema is treated similarly to acute management with H1 antihistamines, addition of H2 antihistamines as needed, and corticosteroids reserved for refractory cases. A regimen cited for refractory cases is prednisone 1 mg/kg/day for 5 days followed by a 7-day taper. Omalizumab (anti-IgE monoclonal antibody) has shown benefit in cases refractory to antihistamines, though it is not FDA-approved specifically for this indication.
For hereditary angioedema long-term prophylaxis, older options include androgens (danazol, stanozolol, oxandrolone, methyltestosterone) and antifibrinolytics, but adverse effects can be significant. Intravenous plasma-derived C1 inhibitors (Cinryze, Berinert) are safe and effective for patients with frequent or severe attacks, though cost may limit access. A twice-weekly subcutaneous C1-INH formulation (Haegarda/CSL830) is FDA-approved for HAE-1 and HAE-2. Lanadelumab and berotralstat (kallikrein inhibitors) have FDA approval for prophylaxis of HAE. In a phase 2 trial, donidalorsen (an antisense oligonucleotide that reduces plasma prekallikrein production) lowered attack rates compared with placebo.
Disposition
More than 85% of patients with nonhereditary acute angioedema achieve symptomatic relief with antihistamines. In chronic nonhereditary angioedema, antihistamines remain the mainstay, and systemic steroids should be reserved for severe or refractory cases. Some patients have recurrence after completing treatment. Chronic angioedema can persist for months to years and may be longer in hereditary angioedema.
Referral
Referral to a dermatologist and/or allergist is recommended for chronic angioedema, hereditary angioedema, and recurrent angioedema. HAE is potentially life-threatening and should be managed by an allergist.
Pearls and Considerations
ACE inhibitor–induced angioedema can occur months or even years after starting the drug. ARB-induced angioedema has been reported, though risk is substantially lower than with ACE inhibitors. About 10% of patients with recurrent angioedema had ACE inhibitor exposure, with a median duration of 1 year before symptoms began. Reported incidence rates per 1000 person-years are approximately 4.38 for ACE inhibitors, 1.66 for ARBs, and notably high for the direct renin inhibitor aliskiren (about 4.67).
Comments
Finding a clear cause is often difficult and can be frustrating. Chronic angioedema is rarely due to an allergic reaction, unlike many acute cases. Hereditary angioedema requires specialized care because of its life-threatening potential.
Basic Information
Urticaria and angioedema are mucocutaneous swellings that occur after release of vasoactive mediators. Urticaria affects the superficial dermis and produces wheals, whereas angioedema results from a transient increase in vascular permeability in mucosal/submucosal or dermal/subcutaneous tissues, leading to deeper tissue swelling.
Synonyms
Angioneurotic edema; Hereditary angioedema (HAE).
ICD-10-CM Codes
T78.3 Angioedema; D84.1 Angioedema, hereditary.
Epidemiology and Demographics
Urticaria and angioedema together have an incidence of about 100 to 3000 per 100,000 persons, and approximately 7.4% of the general population will experience angioedema alone. Around 25% of people will have urticaria and/or angioedema at some point in life. Hereditary angioedema occurs in about 1 in 50,000 persons. African Americans have higher rates of ACE inhibitor–induced angioedema. Angioedema occurs more often in women than men and commonly begins after adolescence, often in the third decade of life. Angioedema can occur with urticaria (about 40%) or alone (about 20%); the remaining ~40% have urticaria alone. For HAE due to C1 inhibitor problems, mean onset is 8–12 years and it rarely presents before age 1.
Physical Findings and Clinical Presentation
Angioedema may be acute or chronic. Acute angioedema is defined as symptoms lasting up to 6 weeks, while chronic angioedema lasts longer than 6 weeks. Typical swelling is nonpruritic, nonpitting, burning, and occasionally painful, involving deep skin layers or submucosal membranes. It is poorly demarcated and most often affects eyelids, lips, tongue, and extremities. It can involve the upper airway and cause respiratory distress, and it can involve the gastrointestinal tract, producing cyclic abdominal pain, nausea, vomiting, and diarrhea. Symptoms generally resolve slowly over hours to a few days.
Etiology and Pathophysiology
Angioedema (with or without urticaria) is broadly classified as histaminergic (mast cell–mediated or idiopathic) or bradykinin-mediated (such as hereditary forms). It is primarily triggered by immune activation with mediator release (histamine, serotonin, bradykinin), causing postcapillary venule inflammation, vascular leakage, and edema in deeper dermis/subcutaneous tissues. Mechanisms can be immunologic or nonimmunologic. IgE-mediated angioedema may follow exposure to foods (milk, eggs, peanuts, shellfish) or drugs (beta-lactam antibiotics, aspirin, NSAIDs, phenytoin, sulfonamide antibiotics, recombinant tissue plasminogen activator). Complement/immune-complex–mediated pathways can activate mast cells and may present as serum sickness.
Hereditary angioedema is subdivided into HAE type 1 (C1 inhibitor deficiency), HAE type 2 (C1 inhibitor dysfunction), and HAE with normal C1 inhibitor function (HAE nC1-INH). HAE-1 and HAE-2 are commonly due to autosomal dominant SERPING1 mutations affecting C1 esterase inhibitor (C1-INH). C1-INH inhibits plasma kallikrein; without adequate inhibition, kallikrein promotes bradykinin generation. Bradykinin is a potent vasodilator that increases capillary permeability and activates pain receptors, so excess bradykinin leads to angioedema. HAE-1 and HAE-2 are typically associated with low C4 due to complement activation, because C1 inhibitor is a major regulatory protein in the complement cascade.
Acquired angioedema is often linked to underlying disease—most commonly B-cell lymphoproliferative disorders—or may occur from autoantibodies against C1 inhibitor. Other triggers include infections (herpes simplex, hepatitis B, Coxsackie A/B, Streptococcus, Candida, Ascaris, Strongyloides), insect bites or stings, stress, physical factors (cold, exercise, pressure, vibration), connective tissue diseases (systemic lupus erythematosus, Henoch–Schönlein purpura), and idiopathic causes. ACE inhibitors can increase kinin activity and precipitate angioedema. Other medication triggers include antibiotics (beta-lactams, quinolones), opiates, and muscle relaxants (succinylcholine).
Diagnosis
A careful history and physical examination usually establish the diagnosis. Extensive laboratory testing is often of limited value.
Differential Diagnosis
Consider anaphylaxis, contact dermatitis, cellulitis, lymphedema, arthropod bite, hypothyroidism, atopic dermatitis, mastocytosis, granulomatous cheilitis, bullous pemphigoid, urticaria pigmentosa, erythema multiforme, epiglottitis, peritonsillar abscess, parasitic infection, and superior vena cava syndrome.
Workup
A broad workup to identify a cause is frequently unrevealing (about 40%). Testing is guided by the clinical history and exam. Basic tests such as CBC, ESR, and urinalysis may help in initial evaluation. Serum total tryptase can help confirm mast cell–mediated anaphylaxis. C4 is usually low in acquired and hereditary angioedema that occurs without urticaria; when C4 is low, measure C1-INH level and functional activity. Rarely, HAE may present with normal C4 but reduced C1-INH. If food allergy is suspected, skin prick testing and/or in vitro specific IgE testing (e.g., ImmunoCAP) may be used. Skin biopsy is generally reserved for chronic angioedema that is refractory to corticosteroids. Stool ova and parasite testing may be considered when parasitic infection is a concern.
Treatment: Nonpharmacologic Therapy
Remove or eliminate the offending agent when possible and avoid known triggers such as cold, stress, and culprit medications (especially ACE inhibitors). Cold compresses can be applied to affected areas for symptomatic relief.
Acute General Treatment
Life-threatening angioedema involving the larynx is treated urgently, although it is important to recognize that bradykinin-mediated angioedema responds minimally to these standard allergic-reaction medications. Typical emergency medications include subcutaneous epinephrine 0.3 mg (1:1000), an H1 antihistamine such as diphenhydramine 25–50 mg IV/IM or cetirizine 10 mg (listed as IV in the source), an H2 blocker such as cimetidine 300 mg IV or famotidine 20 mg IV, and methylprednisolone 125 mg IV.
For mast cell–mediated, nonhereditary angioedema, maintenance therapy centers on H1 antihistamines: cetirizine 10 mg daily (sometimes up to 4× FDA-approved dose), fexofenadine 180 mg daily (sometimes up to 4× dose), hydroxyzine 10–25 mg every 6 hours, or diphenhydramine 25–50 mg every 6 hours. H2 antihistamines can be added (cimetidine 400 mg twice daily or famotidine 20 mg twice daily). Doxepin 25–50 mg at bedtime can be used as an adjunct. Corticosteroids may be used for symptomatic relief in refractory acute cases. Antihistamines are ineffective for hereditary angioedema attacks.
Acute HAE attacks due to C1 inhibitor deficiency respond well to targeted therapies. Approved abortive options include plasma-derived C1 inhibitor concentrate (Berinert), icatibant (Firazyr), a bradykinin B2 receptor antagonist, and ecallantide (Kalbitor), a kallikrein inhibitor. Purified plasma-derived C1-INH replacement is considered effective and safe for acute attacks.
Chronic Treatment
Chronic histaminergic angioedema is treated similarly to acute management with H1 antihistamines, addition of H2 antihistamines as needed, and corticosteroids reserved for refractory cases. A regimen cited for refractory cases is prednisone 1 mg/kg/day for 5 days followed by a 7-day taper. Omalizumab (anti-IgE monoclonal antibody) has shown benefit in cases refractory to antihistamines, though it is not FDA-approved specifically for this indication.
For hereditary angioedema long-term prophylaxis, older options include androgens (danazol, stanozolol, oxandrolone, methyltestosterone) and antifibrinolytics, but adverse effects can be significant. Intravenous plasma-derived C1 inhibitors (Cinryze, Berinert) are safe and effective for patients with frequent or severe attacks, though cost may limit access. A twice-weekly subcutaneous C1-INH formulation (Haegarda/CSL830) is FDA-approved for HAE-1 and HAE-2. Lanadelumab and berotralstat (kallikrein inhibitors) have FDA approval for prophylaxis of HAE. In a phase 2 trial, donidalorsen (an antisense oligonucleotide that reduces plasma prekallikrein production) lowered attack rates compared with placebo.
Disposition
More than 85% of patients with nonhereditary acute angioedema achieve symptomatic relief with antihistamines. In chronic nonhereditary angioedema, antihistamines remain the mainstay, and systemic steroids should be reserved for severe or refractory cases. Some patients have recurrence after completing treatment. Chronic angioedema can persist for months to years and may be longer in hereditary angioedema.
Referral
Referral to a dermatologist and/or allergist is recommended for chronic angioedema, hereditary angioedema, and recurrent angioedema. HAE is potentially life-threatening and should be managed by an allergist.
Pearls and Considerations
ACE inhibitor–induced angioedema can occur months or even years after starting the drug. ARB-induced angioedema has been reported, though risk is substantially lower than with ACE inhibitors. About 10% of patients with recurrent angioedema had ACE inhibitor exposure, with a median duration of 1 year before symptoms began. Reported incidence rates per 1000 person-years are approximately 4.38 for ACE inhibitors, 1.66 for ARBs, and notably high for the direct renin inhibitor aliskiren (about 4.67).
Comments
Finding a clear cause is often difficult and can be frustrating. Chronic angioedema is rarely due to an allergic reaction, unlike many acute cases. Hereditary angioedema requires specialized care because of its life-threatening potential.
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