Adenomas Masquerading as Filiform Polyps: 1635

INTRODUCTION: We present a case of adenomatous filiform-like polyps, raising concern for an unrecognized neoplastic potential in these polyps which typically are of an inflammatory origin. CASE DESCRIPTION/METHODS: A healthy 64-year-old man with a history of tubular adenomas presented for a routine surveillance colonoscopy. He reported feeling well and denied any recent illness including abdominal pain, diarrhea or blood in his stool. He did not have a history of inflammatory bowel disease, infectious colitis, tuberculosis or histiocytosis X. On colonoscopy, a cluster of worm-like mucosal projections was found in his distal transverse colon. The shape was typical of filiform polyps. Under white light and narrow band imaging (NBI), the pit and vascular pattern of each polyp and stalk had a stacked hoop appearance (as opposed to the typical radial array pattern characteristic of an adenoma). The surrounding mucosa appeared normal with a clear demarcation at the base of the stalk. These polyps were completely removed at the base by cold snare polypectomy, including a small margin of normal appearing mucosa. Histopathalogic examination of the resected specimens consisted of primarily adenomatous tissue with a few small fragments of normal mucosa. There were no inflammatory nor serrated polyp features. Three other typical diminutive tubular adenomas were resected elsewhere in the colon. DISCUSSION: Filiform polyps are described as non-neoplastic inflammatory polyps. This is a case of adenomatous filiform-like polyps in a healthy adult without risk factors for inflammatory polyps. They were found in a cluster, which is more typical of filiform polyps rather than adenomas. The polyps appeared to have a stalk but were found to be comprised entirely of adenomatous tissue, necessitating resection at the base rather than transection through the pseudostalk. This unusual finding raises concern that endoscopists should be more cautious of these polyps and complete in their resections as they may have previously unrecognized potential for malignant transformation. A thorough examination of the entire polyp (including the stalk/pseudostalk) for atypical pit and vascular patterns with white light and NBI may aid in differentiating between benign and premalignant growths.