Intraluminal duodenal diverticulum. Report of two cases and review of the literature.

Diverticula rarely occur within the lumen of the duodenum. They arise near the papilla of Vater and extend distally. The diverticulum is lined on both sides with duodenal mucosa, and its eccentric opening is usually proximal in the sac. The diverticulum results from incomplete recanalization of the intestinal lumen after the proliferative epithelial stage in the 7-week embryo and represents either a remnant of one of two channels formed during recanalization or a distal ballooning of a congenital duodenal diaphragm. Although the patient with a diverticulum may be asymptomatic, most patients present with abdominal pain and obstructive symptoms; pancreatitis and gastrointestinal bleeding may be associated with the diverticulum. Barium study shows a characteristic radiolucent halo that represents the wall of the diverticulum. Surgery should be approached with caution because injury to the papilla is a hazard, and in children, coexisting congenital anomalies may be present.