**Author details**

options because of associated side effects and are only used when C1 inhibitor therapy is not available. Weight gain, hepatotoxicity, virilism and hypertension are among the various side

Long-term prophylaxis can be initiated if treatment of acute attacks does not result in adequate symptom control. C1 inhibitor concentrates are recommended as first-line agents. Androgens and tranexamic acid are less favored because of high risk of adverse effects and low treatment

Acquired angioedema is an autoimmune disease characterized by autoantibodies against C1 inhibitor [44]. A lymphoproliferative disorder such as non-Hodgin lymphoma or monoclonal gammopathy or an autoimmune disease is found in many of the cases. These associations suggest that pathological B cell clones may be responsible for acquired angioedema [45].

Acquired angioedema is divided into two types. Type I acquired angioedema is due to massive consumption of C1 inhibitor, presumably by tumor-related immune complexes. Type II acquired angioedema occurs due to the production of anti-C1 inhibitor autoantibodies [25].

Clinical features of acquired angioedema are similar to those seen in hereditary angioedema. Abdominal involvement is less frequent [44]. Absence of family history and late onset of symptoms at 4th decade are distinguishing features [42]. Laboratory evaluation of patients with acquired angioedema reveals low C4 levels and decreased C1 inhibitor activity similar

Treatment of acquired angioedema mostly depends on treatment of the underlying disease [42]. Although response rates are low, treatments used for hereditary angioedema are frequently applied. Acute attacks can be managed by administration of C1 inhibitor concentrate or alternatively by using icatibant or ecallantide. High-dose corticosteroid therapy is used in order to reduce production of autoantibodies but it is frequently ineffective and has many adverse effects. Rituximab has also been shown to be effective in decreasing autoantibody production against C1 inhibitor. Although several reports of patients successfully treated

Drug-induced angioedema is most typically associated with the use of angiotensin-converting enzyme (ACE) inhibitors. Angiotensin receptor blockers, nonsteroidal anti-inflammatory

drugs, fibrinolytics and oral contraceptives can also induce isolated angioedema [18].

to hereditary angioedema; but also decreased levels of C1q [44].

with rituximab exist, the responses can be inconsistent [44, 46].

effects of androgen therapy [43, 44].

22 A Comprehensive Review of Urticaria and Angioedema

efficacy, respectively [43].

**12.2. Acquired angioedema**

*12.2.2. Clinical features*

*12.2.3. Treatment*

**12.3. Drug-induced angioedema**

*12.2.1. Etiology and pathogenesis*

Burhan Engin\*, Muazzez Çiğdem Oba and Server Serdaroğlu

\*Address all correspondence to: burhanengin2000@yahoo.com

Dermatology Department, Cerrahpaşa Medical Faculty, Istanbul University, Istanbul, Turkey
