List 12 causes of a polypoid colonic filling defect.

1. Hyperplastic polyp (most often multiple and less than 5 mm in diameter)
2. Adenomatous polyp
3. Hamartomatous (inflammatory) polyp
4. Filiform polyp
5. Lipoma (usually solitary)
6. Villous adenoma
7. Metastatic lesion (usually multiple)
8. Carcinoid tumor
9. Lymphoma (usually multiple)
10. Feces
11. Gallstone
12. Foreign body