Intestinal polyps or other benign tumors (most common in adults and 2nd most common in general)
Enlarged Peyer patches: individuals with a history of a recent viral infection or immunization (e.g., rotavirus or adenovirus)
Viral stimulation of lymphoid follicles within the small intestine (Peyer patches) can lead to hypertrophy of those areas, which can then act as lead points that become trapped by peristalsis and dragged into a distal portion of the intestine.
The most common location is at the ileocecal junction, as in this patient, and is likely due to a dense concentration of Peyer patches in the terminal ileum.