HEREDITARY ANGIOEDEMA

By Gary M. White, MD


Hereditary angioedema (HA) is an inherited condition in which patients suffer from periodic attacks of angioedema, nausea, as well as abdominal and urinary symptoms.

Clinical

There are recurrent attacks of angioedema which is non-urticarial, non-pitting edema of a localized part of the body. One or more areas may be affected. Any part of the body, upper airway or bowels may be involved. The swelling usually is greatest 24-36 hours after onset and then usually resolves within 72 hours. Most patients have their onset in childhood, but diagnosis is typically delayed for years to decades. The skin may show a prodromal chicken-wire erythema prior to an attack. Attacks may occur spontaneously or triggered by dental or other trauma, stress, infection menstruation or pregnancy. Various medications including estrogen and angiotension-converting enzyme inhibitors may trigger attacks. Involvement of the GIT many lead to intractable abdominal pain, vomiting, nausea, diarrhea, and intestinal obstruction. Involvement of the airway may lead to difficulty breathing and even suffocation.

Workup

During attacks, C2, C4 and CH50 are low. C4 is usually low in between attacks and so it serves as a useful screen.

Treatment

The standard approach to urticaria and angioedema, e.g. antihistamines, epinephrine, is usually not helpful. Prophylactic administration of danazol or stanazol is very helpful as it stimulates production of C1 inhibitor. Patients may be on it long term or as prophylaxis before a dental procedure.

Lanadelumab, an investigational drug and monoclonal antibody that inhibits kallikrein, reduced attacks of hereditary angioedema with C1 inhibitor deficiency by 88-100% in a small, multicenter phase 1 trial [NEJM 2017;376;717].

Treatment of acute attacks may be with infusion of plasma derived or recombinant human C1 inhibitor.

In July 2014, the FDA approved the first recombinant human C1 esterase inhibitor for the treatment of acute angioedema attacks in adult and adolescent patients with HAE. This is an IV infused treatment.

Also subcutaneous icatibant or ecallantide are used. Icatibant (Firazyr®; Rentschler Biotechnologie GmBH, Laupheim, Germany) is a selective bradykinin B2-receptor antagonist, has been available in Denmark since 2008. Ecallantide (Kalbitor®; Dyax Corp, Burlington, Massachusetts) is a potent specific inhibitor of plasma kallikrein.

References

Saxophone Penis. Acute swelling of the penis may cause it to appear like a saxophone. This is most commonly a result of allergic contact dermatitis from rhus, but may also occur in the setting of hereditary angioedema as shown here. Indian Dermatol Online J 2015;6:462-3

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