What is the Clinical Relevance of Filiform Polyposis?

Filiform polyposis (FP) of the colon is an uncommon entity referred to as inflammatory polyposis, or pseudopolyposis. The term FP was first coined by Appelman et al. who used it to describe a syndrome involving the radiographic appearance of numerous long slender worm-like or filiform defects in the colon. The pathogenesis of FP is uncertain. However, FP was generally thought to be associated with the post-inflammatory reparative process. The vast majority of cases occur in the setting of inflammatory bowel disease (IBD), particularly in patients with ulcerative colitis. Crohn’s disease can be presented as giant inflammatory polyposis appearing mass lesion. Although FP typically occurs in patients with IBD, it is important to realize that some cases have been documented in patients without IBD. FP can be sequalae of past bacillary dysentery, necrotizing enterocolitis, enema-induced colitis, ureterosigmoidostomy, stercoral ulcer, Langerhans cell histiocytosis X, and colonic tuberculosis. A case of FP associated with perforated diverticulitis of the sigmoid colon in a patient without IBD was reported with the pathogenesis possibly related to a localized response to cytokines and growth factors generated by the inflamed diverticular mucosa. These polyps represent the postinflammatory reparative process as do those in IBD. Some authors suggest the possibility that the pathogenesis of filiform polyps may not be related to a post-inflammatory reparative process but rather a hamartomatous process because neuromuscular and fibrovascular hyperplasia/disarray were observed in their case series. FP usually has a thin, straight shape resembling the stalks of polyps without the heads. The polyps often present as multiple mucosal projections that can reach up to 9 cm in length and can have bridging between adjacent polyps (Fig. 1). The most common sites affected are the sigmoid colon and rectum. A complete colonoscopy is important, because polyposes can extend as far as the cecum. The polyps can be localized, or