Angioedema.

Kaplan AP.

Source

From the National Allergy, Asthma, and Urticaria Centers of Charleston, Charleston, SC.

Abstract

Angioedema can be caused by either mast cell degranulation or activation of the kallikrein-kinin cascade. In the former case, angioedema can be caused by allergic reactions caused by immunoglobulin E (IgE)-mediated hypersensitivity to foods or drugs that can also result in acute urticaria or a more generalized anaphylactic reaction. Nonsteroidal anti-inflammatory drugs (cyclooxygenase 1 inhibitors, in particular) may cause angioedema with or without urticaria, and leukotrienes may have a particular role as a mediator of the swelling. Reactions to contrast agents resemble allergy with basophil and mast cell degranulation in the absence of specific IgE antibody and can be generalized, that is, anaphylactoid. Angioedema accompanies chronic urticaria in 40% of patients, and approximately half have an autoimmune mechanism in which there is IgG antibody directed to the subunit of the IgE receptor (40%) or to IgE itself (5%-10%). Bradykinin is the mediator of angioedema in hereditary angioedema types I and II (C1 inhibitor [INH] deficiency) and the newly described type III disorder some of which are caused bya mutation involving factor XII. Acquired C1 INH deficiency presents in a similar fashion to the hereditary disorder and is due either toC1 INH depletion by circulating immune complexes or to an IgG antibody directed to C1 INH. Although each of these causes excessive bradykinin formation because of activation of the plasma bradykinin-forming pathway, the angioedema due to angiotensin-converting enzyme inhibitors is caused by excessive bradykinin levels due to inhibition of bradykinin degradation. Idiopathic angioedema (ie, pathogenesis unknown) may be histaminergic, that is, caused by mast cell degranulation with histamine release, or nonhistaminergic. The mediator pathways in the latter case are yet to be defined. A minority may be associated with the same autoantibodies associated with chronic urticaria. Angioedema that is likely to be life threatening (laryngeal edema or tongue/pharyngeal edema that obstructs the airway) is seen in anaphylactic/anaphylactoid reactions and the disorders mediated by bradykinin.

PubMed

Small bowel angioedema due to acquired C1 inhibitor deficiency: a case report and overview.

Dec 2012

Oostergo T, Prins G, Schrama YC, Leeuwenburgh I.

Source

Departments of aInternal Medicine bNephrology, Sint Franciscus Gasthuis, Rotterdam, The Netherlands.

Abstract 

Acquired angioedema is a rare disorder caused by an acquired deficiency of C1 inhibitor. It is characterized by nonpitting, nonpruritic subcutaneous or submucosal edema of the skin, or of the respiratory or gastrointestinal tract. When localized in the gastrointestinal tract, it can cause severe abdominal pain, mimicking an acute surgical abdomen, or chronic recurrent pain of moderate intensity. We report a case of a 48-year-old man presenting with recurrent episodes of hypotension and abdominal pain. Computed tomography of the abdomen showed edema of the small bowel. The first determinations of C1 inhibitor level and activity, measured in a symptom-free period, were normal. Repetition of the laboratory tests in the acute phase, however, showed a low C1 inhibitor level. Further diagnostic work-up indicated an acquired C1 inhibitor deficiency caused by a monoclonal gammopathy. He was treated with tranexamic acid as prophylaxis for his frequent attacks and to date, he has remained symptom free. Acquired C1 inhibitor deficiency is a rare cause of angioedema and is, among others, related to autoantibodies and abnormal B-cell proliferation, for example monoclonal gammopathy. The diagnosis of acquired C1 inhibitor deficiency is made on the basis of the medical history and on the level and activity of plasma C4, C1q, and C1 inhibitor. In case of high suspicion and a normal C1 inhibitor activity, it is recommended to repeat this test during an angioedema attack. Early diagnosis is important for the treatment of severe, potentially life-threatening attacks and to start prophylactic treatment in patients with frequent or severe angioedema attacks.

Gastronoenterology & Hepatology