Clinical Decision Making in Mimickers of IBD: Practice Management From IBD Live

Introduction: Since 2009, a group of inflammatory bowel disease (IBD) specialists have been utilizing “IBD Live,” a weekly live video conference with a global audience of 150-200 participants, to discuss the multidisciplinary management of their most challenging cases. While most cases presented were confirmed as IBD, a substantial number were mimics for which IBD was not the ultimate diagnosis. We have prospectively categorized all IBD Live cases and identified “IBD mimics” with consequent clinical management implications. Methods: Cases have been recorded and archived since May 2018. 371 total cases from May 2018 through February 2023 were reviewed spanning 186 hours. IBD mimics were defined as those cases with features of IBD that ultimately resulted in a non-IBD diagnosis. IBD mimics were analysed and categorized by original suspected diagnosis, diagnostic workup, and the evaluation that led to the correct diagnosis. Results: 306 of the 371 cases discussed were IBD including 193 Crohn’s disease (CD), 107 ulcerative colitis (UC) and 6 IBD-unclassified (IBD-U). 65 (17.5%) cases (Table 1) were mimics with a presumed initial diagnosis of IBD. The evaluations that ultimately resulted in the correct diagnosis included: additional endoscopic biopsies (n=13, 21%), surgical exploration/pathology (n=10, 16.5%), biopsies from outside the GI tract (n=10, 16.5%), genetic and other laboratory testing (n=8, 13%), deeper analysis of patient history, including medication review, family, social, and sexual history (n=8, 13%), imaging (n=5, 8%), balloon enteroscopy (n=5, 8%), and capsule endoscopy (n=2, 3%). We further delineated the diagnostic testing into three categories that ultimately yielded a correct diagnosis: 1) procurement of additional tissue for evaluation, 2) different radiographic or endoscopic evaluation from the original work-up, especially inspection of the small bowel, and 3) more thorough history-taking. Conclusion: In a 5-year period at IBD Live, 17.5% of cases were found to be IBD mimics, many of which originally received advanced therapies for presumed CD or UC. The diverse presentation of IBD cases and the complexity of both assessment and diagnosis necessitates significant consideration of IBD mimics at all times. The substantial differences and often conflicting treatment approaches to IBD vs IBD mimics will directly impact the quality and cost of patient care. Table 1. - IBD mimics presented at IBD live, 2018-2023 Category Mimic N = Diagnosis Systemic diseases CD 21 Vasculitis (7), CVID (2), Sweets (1), EGPA (1), CHAI (1), BADAS (1), Behcet’s (1), eosinophilic esophagitis (1), carcinoid (1), histoplasmosis (1), sarcoidosis (1), amyloidosis (1), PIK3cd (1), adrenal insufficiency (1) Ileal disorders CD 16 BCL (4), IMHMV (2), SCAD (2), follicular lymphoma (1), T-cell lymphoma (1), Kaposi’s sarcoma (1), Meckel’s diverticulum (1), appendiceal carcinoid (1), tropical sprue (1), collagenous sprue (1), autoimmune enteropathy (1) Medication induced UC/CD 8 Immune checkpoint inhibitor (Pembrolizumab [1], Ipilimumab + Nivolumab [2]), chemotherapy (Encorafenib + Binimetinib [1]), Olmesartan (1), Mycophenolate (1), mu-opioid receptor agonist (Kratom [1]), GABA-mimetic (Phenibut [1]) Colonic inflammation UC 5 Ischemic colitis (1), pouchitis (1), diversion colitis (1), CMV colitis (1), STI proctitis (1) Polyposis disorders UC 2 Cronkhite Canada syndrome (1), juvenile polyposis syndrome (1) Obstruction CD 2 Abdominal actinomyces (1), cecal volvulus (1) Peri-anal disease CD 1 Cryptoglandular abscess (1) No diagnosis made UC/CD 11 Unclear at time of IBD Live (9), presumed C-MUSE (1), presumed congenital tailgut cyst (1) Abbreviations: BADAS – bowel-associated dermatosis-arthritis syndrome; BCL – B-cell lymphoma; CHAI – CTLA4 haploinsufficiency with autoimmune infiltrates; C-MUSE – cryptogenic multifocal ulcerous stenosing enteritis; CMV – cytomegalovirus; CVID – common variable immunodeficiency; EGPA – eosinophilic granulomatosis with polyangiitis; IMHMV - idiopathic myointimal hyperplasia of mesenteric veins; SCAD – segmental colitis associated with diverticulitis; STI – sexually transmitted infection; TB – tuberculosis.