[Clinicopathological features of pediatric monogenic inflammatory bowel disease associated with both IL-10 and non-IL-10 pathways: a differential analysis].

Objective: To compare the clinical, endoscopic, and histopathological features of pediatric inflammatory bowel disease (IBD) with IL-10 monogenic defects (IL-10 group) and those with non-IL-10 monogenic defects (non-IL-10 group). Methods: A total of 67 pediatric patients with monogenic IBD diagnosed from 2016 to 2021 were included. All patients were referred by the Children's Hospital of Fudan University, Shanghai, China and pathologically reviewed and genetically confirmed at Sir Run Run Shaw Hospital of Zhejiang University School of Medicine, Hangzhou, China. A comparative analysis of the clinical presentation, endoscopic finding, pathological classification, and histopathological features was performed. A subgroup analysis was also carried out within the non-IL-10 group. Results: Among the 67 cases, 43 in the IL-10 group (predominantly IL10RA/B mutations) and 24 in the non-IL-10 group (CYBB, PIK3CD, LRBA mutations etc.). The median age at diagnosis was significantly younger in the IL-10 group (U=149.0, P<0.001). Endoscopically, the IL-10 group showed more colonic involvement and severe lesions. The IL-10 group more frequently exhibited a Crohn's disease-like pattern (χ2=8.841, P<0.001). Significantly higher rates of active inflammation (χ2=12.26, P<0.001) and transmucosal inflammation (χ2=6.847, P=0.009), moderate-to-severe crypt distortion (χ2=4.541, P=0.033) were also observed as the predominant histopathological features in the IL-10 group. Granulomas and increased intraepithelial lymphocytosis were observed only in the non-IL-10 group. Subgroup analysis of the IL-10 group showed that five patients with PIK3CD mutation had moderate-to-severe crypt distortion and transmural mucosal inflammation whereas three patients with CYBB mutations presented with granulomas, lymphocyte aggregation, and small intestinal villous blunting, without moderate-to-severe crypt distortion or transmucosal inflammation. Conclusions: IL-10-and non-IL-10-mediated monogenic IBD cases exhibit significantly different clinical, endoscopic, and pathological features. The IL-10 group often presents severe infantile/early-childhood colitis, while the non-IL-10 group shows later onset and greater phenotypic heterogeneity.