Ricerc@Sapienza

To identify differences between two cohorts of adult and pediatric patients affected by Crohn’s disease (CD), withregard to lesion location in the small intestine and colon-rectum, lesion activity, and prevalence of perianal disease (PD), usingMRI as the main diagnostic tool.MethodsWe retrospectively reviewed 350 consecutive MRI examinations performed between 2013 and 2016 in outpa-tients or inpatients with histologically proven CD, monitored by the Gastroenterology and Pediatric Units of our Hospital.The magnetic resonance enterography (MRE) protocol for adult and pediatric CD patients routinely includes evaluation ofnine different intestinal segments (from jejunum to rectum) and of the anal canal. Intestinal activity was also calculatedusing a validated score. Perianal disease (PD) was staged. Fisher’sexacttestwasusedandtheoddsratio(OR)wascalculated.ResultsTwo hundred and nineteen out of 350 MRI studies (118 adults and 101 children) were included. The prevalence of PDwas 34.6% in children and 16.1% in adults (OR = 2.8;p= 0.0017). Pediatric patients showed more frequent rectal involvement(29.7% vs 13.5%, OR = 2.7;p= 0.0045) and higher risk of PD in the presence of rectal disease (p= 0.043; OR = 4.5). In pediatricpatients with severe colorectal disease, the prevalence of PD was twofold (86.7% vs 40%;p= 0.072). Using the clinical Montrealclassification for lesion location, no significant differences emerged between the two patient populations.ConclusionsMRI showed a significantly higher prevalence of rectal involvement and perianal disease in the pediatric population.These results may have a relevant clinical impact and deserve further investigation.Key Points•To our knowledge, this is the largest morphological comparative study available in the literature using MRI as the maindiagnostic tool to compare adult patients and children with Crohn’sdisease.•Our study showed significant differences between adults and children: a higher prevalence of rectal and perianal fistulousdisease (PD) in pediatric patients and an increased prevalence of PD in the presence of severe colon-rectum involvement.•The association of rectal and perianal disease implies a poorer clinical prognosis and a higher risk of disabling complicationsin pediatric patients.