Tissue and peripheral eosinophilia as predictors for disease outcome in children with ulcerative colitis

Background Eosinophils are implicated in the pathogenesis of ulcerative colitis. Aims To evaluate the magnitude of mucosal and blood eosinophils in newly diagnosed pediatric ulcerative colitis patients and its significance in predicting disease outcomes. Methods We retrospectively evaluated colorectal biopsies of 96 pediatric patients with ulcerative colitis and 50 age- and sex-matched controls. Samples were taken from diseased areas of the colon and examined by a gastrointestinal pathologist. The most inflamed site was used for assessment of mucosal eosinophils. Results Samples from 96 diagnostic and 70 follow-up colonoscopies were evaluated. Median age was 13.3 years (IQR 10.1–15.3). Median duration of follow-up was 12.8 years (IQR 7.2–17.1). Median number of tissue eosinophils at diagnosis was 45 (IQR 22–73) compared to 10 eosinophils (IQR 8–25) during histologic remission (p < 0.0001). Peripheral absolute eosinophil counts correlated with tissue inflammation and eosinophilia (p = 0.001). Mucosal eosinophilic infiltration (p = 0.02) and peripheral eosinophilia (p = 0.04) was associated with clinical severity at diagnosis. Multivariate analysis showed that severe eosinophilic infiltration is associated with corticosteroid therapy following diagnosis (p = 0.04) but not with long-term risk for step-up therapy or colectomy. Conclusion Tissue and peripheral eosinophilia correlate with ulcerative colitis severity at diagnosis and with short-term corticosteroid requirement but not with long-term outcomes.