Question: A 62-year-old man underwent colonoscopy for evaluation of low abdominal discomfort and tenesmus of 1 month’s duration. His past medical history was negative for inflammatory bowel disease, intestinal tuberculosis, or infectious colitis. In addition, he had no history of gastrointestinal bleeding. Physical examination was unremarkable and all laboratory test results were within normal limits. On colonoscopy, about 11 × 0.6-cm, long, thin, vermiform polyp was found on cecum (Figure A). It was removed by snare after applying a hemoclip at the base of the polyp (Figure B). There were 7 more polyps found throughout the colon and were diagnosed as tubular adenomas with low-grade dysplasia histologically after resection. What is the diagnosis of the long thin vermiform polyp? See the Gastroenterology web site (www.gastrojournal.org) for more information on submitting your favorite image to Clinical Challenges and Images in GI. Histopathologic examination of the resected polyp revealed polypoid finger-like projections into the lumen covered by normal mucosa and submucosa, which was consistent with filiform polyp (Figure C; stain: hematoxylin and eosin; original magnification, ×40). Although there were several reactive lymphoid aggregates in the mucosa, there was no distortion of mucosal architecture (Figure D; stain: hematoxylin and eosin; original magnification, ×200). Filiform polyposis of the colon is an uncommon condition of unknown pathogenesis that is considered to arise as a result of a benign postinflammatory process. On colonoscopy, the polyps typically appear as multiple, slender, worm-like projections of submucosa covered by normal mucosa. Filiform polyposis has mostly been reported in patients with intestinal tuberculosis, histiocytosis X, or inflammatory bowel disease, including Crohn’s disease and ulcerative colitis.1Rozenbajgier C. Ruck P. Jenss H. et al.Filiform polyposis: a case report describing clinical, morphological, and immunohistochemical findings.Clin Investig. 1992; 70: 520-528Crossref PubMed Scopus (20) Google Scholar It is rarely discovered in patients without underlying colonic disease or history of inflammation. There have been several case reports about filiform polyposis without history of inflammatory bowel disease, but they were either multiple or presented with symptoms such as diarrhea or gastrointestinal bleeding.1Rozenbajgier C. Ruck P. Jenss H. et al.Filiform polyposis: a case report describing clinical, morphological, and immunohistochemical findings.Clin Investig. 1992; 70: 520-528Crossref PubMed Scopus (20) Google Scholar, 2Macaigne G. Boivin J.F. Cheaib S. et al.[Single filiform polyp revealed by severe haemorrhage in a patient with normal colon. Report of a case and review of the literature].Gastroenterol Clin Biol. 2006; 30: 913-915Crossref PubMed Google Scholar Only 1 report presented a case of a single filiform polyp in transverse colon without additional polyps in a patient without history of inflammatory bowel disease.3Kang H.M. Kang Y.S. Kim S.H. et al.Single filiform polyp in asymptomatic healthy Korean without history of inflammatory bowel disease.Endoscopy. 2007; 39: E333-E334Crossref PubMed Scopus (6) Google Scholar However, in our case, the single filiform polyp was present with 7 other tubular adenomas with low-grade dysplasia. In addition, we believe that the single filiform polyp was an incidental finding and not the cause of his presenting symptom.