Acute abdomen in a patient with homozygous type I hereditary angioedema: rapid improvement in computed tomography scans after C1 inhibitor replacement.

Hereditary angioedema (HAE) due to C1-inhibitor de ciency is a rare autosomal dominant disease characterized by recurrent episodes of transient localized swelling of the subcutaneous and/or mucosal tissues that can occur anywhere in the body. Acute abdominal pain due to mucosal swelling of the gut is one of the most common presentations of HAE, leading frequently to unnecessary abdominal surgery such as exploratory laparotomy and appendectomy. We report the case of a patient with a previous diagnosis of HAE who experienced an episode of severe acute abdominal pain with striking computed tomography (CT) ndings that resolved rapidly after intravenous infusion of a C1 esterase inhibitor (C1-INH) concentrate and no other therapy. The patient had type I HAE in homozygosis, ie, a mutation affecting the coding region of C1INH in both alleles, which is extremely rare. His only treatment was low-molecular-weight heparin injections for acute angioedema attacks. The patient was a 22-year-old man who presented at the emergency department with diffuse abdominal pain that had begun the previous day. He had no other gastrointestinal or general symptoms. He had a history of HAE with a speci c familial homozygous mutation in the C1INH gene, which was the subject a previous publication by our group [1] and a detailed editorial comment [2]. The patient was allergic to nuts and rosaceae and smoked 10 cigarettes a day. Initially, he received therapy with stanozolol (2-4 mg/d) for several months, although this was withdrawn because of undesirable androgenic effects (including alopecia) and a poor response Figure. Abdominopelvic computed tomography scan before and after intravenous infusion of C1-INH. Coronal reconstruction. A, Diffuse hypodense thickening of the ascending colon and ileocecal region before therapy. B, Thickening of the transverse colon before therapy. C and D, Marked reduction in infl ammatory swelling of the transverse colon, ascending colon, and cecum 12 hours after intravenous infusion of C1-INH. A B