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Acquired C1 inhibitor deficiency: Clinical manifestations, epidemiology, pathogenesis, and diagnosis

Marco Cicardi, MD
Section Editor
Sarbjit Saini, MD
Deputy Editor
Anna M Feldweg, MD


Acquired angioedema due to deficiency of C1 esterase inhibitor, also called acquired angioedema and abbreviated C1INH-AAE, is a rare syndrome of recurrent episodes of angioedema, without urticaria, which is associated with B cell lymphoproliferative disorders in some patients [1]. Angioedema typically affects the skin or mucosal tissues of the upper respiratory and gastrointestinal tracts. The swelling is self-limited, although laryngeal involvement may cause fatal asphyxiation. Clinically, this disorder is very similar to hereditary angioedema, although acquired angioedema develops in older patients and is frequently associated with underlying disease, whereas the hereditary disorder presents in younger patients who are otherwise healthy [2].

This topic review will discuss the clinical manifestations, epidemiology, pathogenesis, and diagnosis of acquired C1 inhibitor deficiency. The management and prognosis of this disorder are reviewed separately. (See "Acquired C1 inhibitor deficiency: Management and prognosis".)

Hereditary angioedema is discussed separately. (See "Hereditary angioedema: Pathogenesis and diagnosis" and "Hereditary angioedema: Epidemiology, clinical manifestations, exacerbating factors, and prognosis" and "Hereditary angioedema: Treatment of acute attacks" and "Hereditary angioedema: General care and long-term prophylaxis".)


Acquired angioedema due to deficiency of C1 esterase inhibitor, also called acquired angioedema and abbreviated C1INH-AAE, is rare, and the precise incidence is not known.

In the group of patients referred to the author's specialty center in Milan for angioedema due to C1 inhibitor deficiency since 1976, 77 had acquired and 675 had hereditary forms of the disease with a ratio of 1:8.8 [3,4].

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Literature review current through: Nov 2017. | This topic last updated: Aug 29, 2016.
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