MRI reveals different Crohn's disease phenotypes in children and adults.

OBJECTIVES

To identify differences between two cohorts of adult and pediatric patients affected by Crohn's disease (CD), with regard to lesion location in the small intestine and colon-rectum, lesion activity, and prevalence of perianal disease (PD), using MRI as the main diagnostic tool.

METHODS

We retrospectively reviewed 350 consecutive MRI examinations performed between 2013 and 2016 in outpatients 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 of nine different intestinal segments (from jejunum to rectum) and of the anal canal. Intestinal activity was also calculated using a validated score. Perianal disease (PD) was staged. Fisher's exact test was used and the odds ratio (OR) was calculated.

RESULTS

Two hundred and nineteen out of 350 MRI studies (118 adults and 101 children) were included. The prevalence of PD was 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 pediatric patients with severe colorectal disease, the prevalence of PD was twofold (86.7% vs 40%; p = 0.072). Using the clinical Montreal classification for lesion location, no significant differences emerged between the two patient populations.

CONCLUSIONS

MRI 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 main diagnostic tool to compare adult patients and children with Crohn's disease. • Our study showed significant differences between adults and children: a higher prevalence of rectal and perianal fistulous disease (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 complications in pediatric patients.