A 35-year-old woman, with a history of multiple admissions for acute pancreatitis since the age of 17 years, visited our hospital with a chief complaint of epigastric pain. She was diagnosed with intussusception of the upper small intestine based on abdominal contrast-enhanced computed tomography findings (Figure 1). Laboratory data were as follows: white blood cell count, 13930/?L; amylase level, 587 U/ L; and C-reactive protein level, 0.24 mg/dL. She was hospitalised for further examination and treatment. Upper gastrointestinal (UGI) endoscopy showed a diverticulum that contained food in the descending duodenum (Figure 2). A UGI contrast study revealed a barium-filled sac within the duodenum (Figure 3); therefore, a diagnosis of an intraluminal duodenal diverticulum (IDD) was made. Mechanical stimulation due to distension caused by food was thought to have caused both the intussusception and the patient’s previous episode of pancreatitis. The diverticulum, which emerged from the duodenal lumen below the papilla of Vater, was surgically removed to prevent relapse of the conditions (Figure 4). The resected diverticulum was covered with a mucous membrane, and the inherent muscular layer was lost in the diverticulum (Figure 5). The patient had no symptoms postoperatively.

IDD is a rare congenital anomaly [1]. Its nonspecific symptoms make diagnosis difficult and necessitate appropriate imaging [2]. The ‘windsock sign’ is typical in a UGI contrast study of a patient with IDD [2,3]. IDD should be suspected when patients present with recurrent epigastric pain and pancreatitis of unknown aetiology.