Hereditary angioedema presented as isolated ascending and transverse colon swelling mimicking acute abdomen.

Hereditary angioedema (HAE) is a rare autosomal dominant condition characterized by C1-INH gene mutations, leading to recurrent angioedema episodes affecting various body parts, including the gastrointestinal tract. This case report describes a 24-year-old female presenting with symptoms mimicking an acute abdomen, characterized by severe abdominal cramps, anorexia, and diarrhea, with a significant past medical history of angioedema flares and emergency intubation for asphyxiation at age 11. Despite initial treatment with antihistamines showing no improvement, her symptoms spontaneously resolved. Further investigation revealed low complement C4 levels and reduced C1-INH function, confirming HAE with an unusual isolated involvement of the ascending and transverse colon. This case underscores the importance of considering HAE in patients presenting with acute abdominal symptoms, especially with a history suggestive of angioedema. It highlights the need for emergency physicians and gastroenterologists to be aware of HAE's clinical manifestations to avoid misdiagnosis and unnecessary interventions. Moreover, the case emphasizes the significance of patient education on recognizing symptoms and seeking timely medical attention to prevent severe complications. This report adds to the existing literature by detailing an uncommon presentation of HAE, aiming to enhance early diagnosis and management of this potentially life-threatening condition.