P243 The different role of histology in ulcerative colitis and Crohn’s disease: a retrospective study in a single referral centre

In addition to endoscopic evaluation, a consistent set of studies has demonstrated an important role for histology in ulcerative colitis (UC) patients, both for diagnosis and in follow-up, while in Crohn’s disease (CD) evidence are scantier. The aim of the study was to investigate the different role of histological evaluation in CD and UC patients, in a single referral centre. Data of 86 IBD patients in follow-up at IBD Outpatient Clinic in San Giovanni-Addolorata Hospital in Rome (2016–2017) were retrospectively evaluated. We included only patients (n = 30 UC and 30 CD) who had a visit and a colonoscopy within 1 month, and who had a 1-year follow-up visit. Active symptoms, endoscopic activity, histological inflammatory activity and specificity, and flare occurrence at 1 year of follow-up, were considered as dichotomous variables (0–1). In the histological report, neutrophilic infiltrate, criptitis and criptic abscesses were considered features of active inflammation, and basal plasmocytosis, mucin depletion, structural disarray and granulomata were considered specific features for IBD. Moreover, in patients with established diagnosis of IBD (12 CD and 14 UC), the presence of specific histological features at the first colonoscopy was evaluated, to investigate the role of histology for the initial diagnosis in those patients. In patients in follow-up, a significant higher rate of UC patients showed full concordance (specificity and activity) between histological and endoscopic evaluation comparing with CD patients [26/30(87%) vs. 12/30(40%), p < 0.005]. In IBD patients in follow-up, 72% of UC and 57% of CD patients showed specific histological IBD features. Eighty-four per cent of UC and 58% of CD patients displayed concordance between endoscopic and histological inflammatory activity. In UC, but not in CD, both endoscopic and histological inflammatory activity correlated with the presence of active symptoms of disease (p < 0.001 and p < 0.05, respectively). No significant different rate of flare at 1 year was observed in patients with endoscopic/histological features or symptoms of active vs. inactive disease, both in UC and CD. In the first colonoscopy performed for suspected IBD, specific diagnostic features were found in 86% of UC and 67% of CD patients. in UC patients, histological evaluation consistently correlated with endoscopic and clinical features of active disease, and showed an elevated specificity both for the diagnosis and in the follow-up. In CD patients, correlation with histology and endoscopic/clinical features was less impressive. In a referral centre histological evaluation has a potential relevant role in IBD diagnosis and follow-up.