Imaging description

Angioedema is a transient inflammatory reaction due to vascular leak that is related to urticaria, but affects the subcutaneous or submucosal tissues of the body while urticaria occurs in the skin only (although angioedema and urticaria may co-exist) [1]. Angioedema is likely due to the release of inflammatory mediators from mast cells and/or the activation of complement or kinin systems [2]. All parts of the body may be affected, including the eyes, lips, upper respiratory tract, and bowel. Angioedema of the bowel is often clinically non-specific and so awareness of the radiological findings is particularly important. At CT, angioedema of the bowel is characterized by transient wall thickening, mucosal hyperemia, mural stratification, prominent mesenteric vessels, and ascites (Figures 58.1 and 58.2) [3].

Importance

Angioedema is rare, and in one study accounted for only 1 to 4% of 6107 patients seen in a large emergency department with acute allergic reactions [4]. Hereditary angioedema has an estimated prevalence of 1 in 50,000 to 150,000 [3]. However, the condition is likely under-diagnosed and cases may go unrecognized for many years – in a series of 235 patients with C1-inhibitor deficiency, 34% had undergone abdominal surgery before the diagnosis was established [5, 6]. Knowledge of the CT findings may facilitate correct diagnosis, potentially averting unnecessary intervention and promoting appropriate workup and therapy (Figure 58.3).