C1 inhibitor deficiency and angioedema of the small intestine masquerading as Crohn's disease.

A case of C1 inhibitor deficiency presenting as localized edema of the small intestine is described. A 16-year-old, previously healthy woman presented with recurrent attacks of abdominal pain and vomiting following minor abdominal trauma. Investigations including computed tomography scan and barium studies confirmed localized edema of the jejunum. At laparoscopy, Crohn's disease was suspected; however, a subsequent enteroscopy was normal. Complement levels revealed a low C4 level, and C1 inhibitor deficiency was later confirmed. Attacks of abdominal pain began after starting oral contraceptives and have not returned since stopping the birth control pill. This rare cause of abdominal pain is examined, and C1 inhibitor deficiency and angioedema are reviewed.