Evolution of filiform polyposis from classical pseudopolyposis in a pediatric ulcerative colitis patient

Filiform polyposis (FP) is a morphologic variant of pseudopolyposis associated with inflammatory conditions of the gastrointestinal tract, namely, inflammatory bowel disease. Pediatric cases are uncommon in the literature. Here, we present a pediatric patient with FP arising from ulcerative colitis (UC). He initially presented at 7 years of age for an acute UC flare and was found to have classical pseudopolyposis. A follow-up colonoscopy at age 9 showed the evolution of classical pseudopolyposis to FP. The patient clinically improved with sulfasalazine monotherapy and remained in remission based on consistent pediatric ulcerative colitis activity index scores of zero and normal-range inflammatory markers. Repeat surveillance colonoscopy at age 14 showed persistent and diffuse FP in the background of healthy colonic mucosa. This case documents the development of FP from classical pseudopolyps in the setting of an asymptomatic patient in clinical remission.