Intraluminal duodenal diverticulum associated with trisomy 21.

An intraluminal duodenal diverticulum is an uncommon congenital abnormality that may produce intermittent ostruction. The true pathogenesis of this lesion is still disputed, but it probably results from ballooning of a congenital web or diaphragm with prolonged peristalsis. An intraluminal "wind sock"-like structure filed with barium and surrounded by a radiolucent halo is the classic and diagnostic radiologic appearance. An association with trisomy 21 is made.