Recurrent Intestinal Angioedema with Normal C1-Inhibitor: A Case Report

Background and Objectives: Angioedema is a non-pitting edema of the submucosal layer which can be acquired or inherited and usually presents with hives. Intestinal angioedema is rare and can mimic other acute gastrointestinal disorders. It is typically associated with a lack or dysfunction of C1-inhibitor, with a small number of cases having normal C1-inhibitor function. We present a rare case of chronic recurrent intestinal angioedema in a patient with normal C1-inhibitor function who did not respond to icatibant therapy. Case presentation: A 56-year-old woman presented with 3 days of abdominal pain, nausea, vomiting, and diarrhea. She denied a history of allergies and reported a 30-year history of similar episodes requiring hospitalization. Initial evaluation demonstrated normal C4 and C1 esterase inhibitor function with negative gastrointestinal bacterial and viral panel. A CT of the abdomen and pelvis demonstrated acute diffuse bowel thickening and prominent mesenteric lymph nodes. MRI demonstrated inflammation of the small and large bowel. EGD and colonoscopy findings were normal. She was diagnosed with intestinal angioedema and started on icatibant without significant improvement. Her symptoms resolved after 3 days of supportive therapy and resolution of inflammation was noted on imaging. She was discharged home with allergy and immunology follow-up. Conclusions: Intestinal angioedema is under-recognized and presentation can overlap with other pathologies of the GI tract. Extensive work up is needed during the first episode of an attack and complement levels should be checked in all patients. Appropriate classification is important as it dictates therapy. However, ambiguous cases like ours sometimes cannot be classified into any specific category.