S2885 A True Gut Feeling: Recurrent Abdominal Pain as the Presenting Symptom of Hereditary Angioedema

INTRODUCTION: Hereditary angioedema (HAE) is a rare, autosomal dominant disorder. Recurrent episodes of abdominal pain without any apparent clinical findings can lead to misdiagnosis of functional bowel disorder, neuropsychiatric disorder or even acute abdomen leading to unnecessary surgery. Gastrointestinal attacks resulting from bowel wall edema are commonly seen and might be the principal presentation of HAE. Symptoms can vary from crampy abdominal pain, bloating, nausea, vomiting or diarrhea. Nonspecific symptoms lead to delay in diagnosis increasing morbidity and mortality. We report a case of a middle-aged female presenting with relapsing and remitting abdominal pain, precipitating diagnostic dilemma. CASE DESCRIPTION/METHODS: A 45-year-old female presented to the emergency room withnew onset acute severe abdominal pain. Imaging included abdominal CT with findings of 40 cm segment of inflamed ileum, ascites and a possible internal hernia. Laboratory work-up remarkable for mild leukocytosis, otherwise normal liver enzymes, negative EBV and CMV. Patient underwent exploratory laparotomy showing inflamed but viable bowel, no other pathology. Further recommendations requested for gastroenterology evaluation to rule out Crohn’s disease. Symptoms self-resolved and was discharged home. Two months later returns with same clinical presentation. Repeat CT showed similar findings. Steroids were given empirically leading to prompt improvement of symptoms. MRI was obtained showing improvement of ileitis. Furthermore, she reported that her mother and grandmother could not use OCPs due to side effects of “abdominal attacks”. Triggering further testing for C1 esterase inhibitor and C4 levels, which were unremarkable; however, positive for F12-NG mutation. Patient confirmed starting using OCPs 5 months prior to her first abdominal attack. DISCUSSION: Hereditary angioedema is a rare disease that can frequently be overlooked. Occasionally, symptoms are limited to the gastrointestinal tract, presenting as acute abdominal attacks. These are very sensitive to hormonal changes, as seen in our patient with OCP use, particularly in families with F12-NG mutations, presenting with normal C1-inh and C4.Thus, these female patients should be educated to avoid OCPs along with genetic counseling, and effective interdisciplinary communication is necessary to establish care during pregnancy. High level of suspicion and understanding its clinical presentation is imperative to achieve early diagnosis and avoid invasive procedures.Figure 1.: Axial images through the mid and lower abdomen of an IV contrast enhanced CT of the abdomen and pelvis in the portal venous phase demonstrating acute small bowel wall inflammation as evidenced by wall thickening, mucosal and muscularis propria hyperenhancement with edematous submucosa (halo sign), and mild surrounding fat stranding.Figure 2.: Axial images through the mid and lower abdomen of an IV contrast enhanced CT of the abdomen and pelvis in the portal venous phase demonstrating acute small bowel wall inflammation as evidenced by wall thickening, mucosal and muscularis propria hyperenhancement with edematous submucosa (halo sign), and mild surrounding fat stranding.