Crohn's-like clinical and pathological manifestations of giant inflammatory polyposis in IBD: A potential diagnostic pitfall

Abstract

Background & aimsGiant inflammatory polyposis (GIP), characterized by mass-like agglomerations of inflammatory polyps, is a rare complication of inflammatory bowel disease (IBD). We reviewed a series of cases of GIP to determine its diagnostic impact on the clinical and pathologic distinction between ulcerative colitis (UC) and colonic Crohn's disease (CD). MethodsAll colons with GIP resected over a 13-year period were identified prospectively and the corresponding clinical and pathologic records were reviewed. ResultsTwelve cases of GIP were identified, accounting for 0.8% of colectomies for IBD during the same time interval. Preoperatively, 6 (50%) patients were diagnosed with UC, 2 (17%) with CD and 4 (33%) with indeterminate colitis (IC). Postoperatively, 6 of the diagnoses (50%) were revised based on strict histopathologic criteria: all 4 diagnoses of IC to UC, one diagnosis of CD to UC, and one diagnosis of UC to CD, for a total of 10 diagnoses of UC (83%) and two of CD (17%). Significantly, 7 of 10 cases with postoperative diagnoses of UC (70%) had Crohn's-like transmural inflammation exclusively within the polyposis segments attributed to fecal entrapment and stasis and accounting for the Crohn's-like clinical complications in these cases. ConclusionsThis case series of GIP, the largest reported from a single center, highlights the high rate of Crohn's-like clinical and pathological manifestations of GIP and their potential to confound the accurate classification of patients with IBD. A diagnosis of UC should not be amended to CD based on the findings of the polyposis segment alone.