Nodular lymphoid hyperplasia of terminal ileum: how to avoid overdiagnosis of Crohn's terminal ileitis in MR enterography?

ABSTRACT

PURPOSE: To investigate the magnetic resonance enterography (MRE) characteristics of nodular lymphoid hyperplasia (NLH) and Crohn's terminal ileitis (CTI). METHODS: Of 1552 MREs from November 2011 to July 2018, 61 individuals with biopsy-proven NLH (n = 24) and CTI (n = 37, 27 with active CTI) were selected based on the inclusion criteria. NLH cases were also followed up for median (range) of 40 (21-61) months. Two board-certified radiologists, blind to clinical data and diagnosis, reviewed MRE in consensus. Conventional, morphological, enhancement, and diffusion parameters were assessed. Mann-Whitney, χ2, and logistic regression analyses were conducted. RESULTS: No NLH patient developed inflammatory bowel disease or lymphoproliferative disorders during the follow-up. Serosal surface irregularity (65% vs. 8%), pseudo-diverticula (27% vs. 0), and mesenteric fat involvement (38% vs. 4%) were more frequent in CTI than NLH (p < 0.01), while mucosal nodularity was more prevalent in NLH (71%) than CTI (19%) (p < 0.001). The upstream luminal diameter (15.0 vs. 12.5 mm, p = 0.015) and mural thickness (6.0 vs. 4.0 mm, p < 0.001) of the terminal ileum showed higher values in CTI than NLH. CONCLUSIONS: Unlike enhancement and diffusion parameters, morphological features (mucosal nodularity, serosal surface irregularity, and mesenteric fat involvement) could distinguish NLH from CTI regardless of CTI activity.