Hereditary Angioedema Presenting as Recurrent Abdominal Pain: A Diagnostic Challenge

Abstract

Background: This case report highlights the importance of prompt recognition of hereditary angioedema (HAE) in patients with recurrent abdominal attacks that may mimic surgical emergencies and lead to unnecessary interventions. Case Presentation: A 29-year-old man presented with severe recurrent abdominal pain associated with loose stools. Each episode lasted 3-5 days and resolved spontaneously. Further enquiry revealed a 16-year history of recurrent angioedema involving the face, lips, oral cavity, dorsum of both hands, and large joints of the lower limbs, with multiple episodes each year. The long-standing symptoms and diagnostic delay raised strong clinical suspicion of C1 esterase inhibitor (C1-INH) deficiency. Contrast-enhanced computed tomography of the abdomen and subsequent colonoscopy were performed during an attack. Laboratory evaluation showed low serum C4, low quantitative C1-INH levels, and markedly reduced C1-INH functional activity, findings consistent with Type 1 HAE. The patient was subsequently started on tranexamic acid. At follow-up, he was clinically improved, with complete resolution of symptoms and no recurrence of attacks. Conclusion: This case highlights the importance of recognising abdominal attacks in patients with C1-INH deficiency. Such attacks can be debilitating, may mimic surgical emergencies, and may contribute to prolonged diagnostic delay. Careful recognition of the recurrent pattern of abdominal symptoms together with non-pruritic, non-pitting angioedema and appropriate biochemical testing can support timely diagnosis and help avoid unnecessary interventions.