Case presentation
The 52-years-old Japanese man who had undergone laparoscopic surgery for a duodenal ulcer 12 years ago presented with upper abdominal pain. His symptoms persisted from the morning of that day. On arrival at the emergency room, his blood pressure was 166/92 mmHg, pulse was 65 beats per minute, and oxygen saturation was 98% on room air. He experienced mild discomfort, with a body temperature of 39.0 °C. No signs of peritoneal irritation were noted. The laboratory data showed a high white blood cell count of 21,200/uL but c-reactive protein level of 0.3 mg/dL was at normal level (<1.0 mg/dL). Abdominal computed tomography (CT) revealed an expanded duodenal diverticulum inside the second portion of the duodenum and free air in the retroperitoneum outside the diverticulum (Fig. 1). Duodenal ulcer perforation was suspected based on the patient’s history. However, CT imaging was most likely caused by perforation of a duodenal diverticulitis because past CT showed an existing duodenal diverticulum. Because there were no symptoms of peritoneal irritation, broad-spectrum antibiotics, placement of a nasogastric tube, and use of proton pump inhibitors (PPIs) were initiated. After 2 days of admission, the inflammatory findings did not improve; therefore, endoscopic drainage was performed. On endoscopy, a duodenal diverticulum with a fixed large phytobezoar and a large amount of pus was observed (Fig. 2a). Because the bezoar blocked the orifice of the duodenal diverticulum, it perforated the retroperitoneum and became an abscess cavity. The phytobezoar was so large and of hard consistency that endoscopic removal during a single session was difficult. A 7.5 Fr endoscopic nasobiliary drainage (ENBD) catheter was placed in the duodenal diverticulum. Contrast injection showed a large translucent image of the diverticulum (Fig. 3a). The duodenal diverticulum was washed daily with 20 mL of saline from the ENBD catheter. As a result, the fever resolved and inflammatory findings improved. On the second endoscopy, since the phytobezoar was slightly softer than that on the previous endoscopy, it was gradually eliminated by crushing with forceps (Fig. 2b). However, part of the phytobezoar remaining deep in the cavity could not be completely removed, so a 6 Fr ENBD catheter was placed in the cavity again (Fig. 3b). The following day, saline was injected through the tube to clean the abscess cavity, and the phytobezoar was completely removed by a third endoscopic treatment (Fig. 2c). The patient was discharged from the hospital without any complications. After 3 months, subsequent upper gastrointestinal endoscopy showed that the cavity of the duodenal diverticulum had shrunk and the mucosa of the diverticulum had regenerated (Fig. 2d).