Background and aims: Ulcerative proctitis (UP) is an uncommon presentation in pediatric patients with ulcerative colitis. We aimed to characterize the clinical features and natural history of UP in children, and to identify predictors of poor outcomes. Methods:The retrospective cohort study involved 37 sites affiliated with the IBD Interest group of ESPGHAN. Data were collected at different time points from patients aged<18 years diagnosed with UP between 01/01/2016-31/12/2020. Results:We identified 250 patients with UP with a median follow-up of 2.7 (IQR 1.7-3.9) years. were included. Median age at diagnosis was 14.5 (IQR 12.3-15.9) years. Median follow-up was 2.7 (IQR 1.7-3.9) years. The most common presenting symptoms were bloody stools (93.6%), abdominal pain (60.4%) and diarrhea (52.8%). At diagnosis, the median pediatric ulcerative colitis activity index (PUCAI) score was 25 (IQR 20-35), the median fecal calprotectin level was 720 mcg/g (IQR 310-1800), notably 16 patients (11.7%) had a calprotectin level <100mcg/g. Most patients exhibited moderate-severe endoscopic inflammation. Oral, topical or By the end of induction, administration of orally, topically or combination of both resulted in clinical remission rates of 51.8%, 50.0% 73.3%, respectively at weeks 8-12?. The rates of treatment escalation to biologics at 1, 3 and 5 years were 10.6%, 22.7% and 44.6%. in multivariate analysis, Tthe PUCAI score at diagnosis was highly associated with escalation of therapy and subsequent events with acute severe colitis eventsand or IBD-associated admissions (multivariate analysis). By the end of follow-up, 3.4% of patients underwent colectomy. Cecal patch (P=0.009), higher PUCAI score (P=0.009) and lack of steroid-free clinical remission (P=0.005) by the end of induction were associated with proximal disease extension, identified in 48.3%.. Conclusion:Pediatric patients with UP exhibit high rates of proximal disease extension and treatment escalation.

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BACKGROUND Adult studies suggest that patients with isolated colonic Crohn’s disease (L2 CD) exhibit unique characteristics differentiating them from patients with ileo-cecal (L1) CD and ulcerative colitis (UC). We aimed to characterize clinical features and outcomes of paediatric patients with L2. METHODS Retrospective data was collected through the Porto IBD group of ESPGHAN on paediatric patients with L2, L1 or UC at different time-points. Outcome measures included time to 1st flare, hospital admissions, initiation of anti-TNFa drug, stricture and surgery. RESULTS Three hundred patients were included: 102 L1, 94 L2 and 104 UC. Rates of hematochezia at presentation were 14.7%, 44.7% and 95.2%, while rates of fever were 12.7%, 26.6% and 2.9%, for patients with L1, L2 and UC, respectively (P&lt;0.001 for all comparisons). Skip lesions were identified in 65% of patients with L2, and granulomas in 36%, similar to L1 patients. Rates of ASCA and pANCA positivity significantly differed between the groups: 25.4% and 16.7% for patients with L2, compared with 55.2% and 2.3%, and 1.8% and 52.9% for patients with L1 and UC, respectively. Response rates to exclusive enteral nutrition were comparable between L1 and L2 (78.3-82.4%), as was the response to oral steroids (70.4-76.5%) in the three groups. While times to 1st flare and admission were similar between groups, patients with L1 were commenced on anti-TNFa earlier. Moreover, stricturing phenotype and need for colectomy were very rare in patients with L2. CONCLUSIONS Significant differences are observed in the clinical presentation and outcomes of paediatric patients with L2, compared to patients with L1 and UC.

Background Isolated colonic (L2) Crohn’s disease (CD) in adults is thought to have unique clinical and genetic features compared with ileal (L1) CD and ulcerative colitis (UC). Similar studies in paediatrics are scarce. Our goal was to characterize the clinical features of paediatric patients with isolated colonic CD and compare them to patients with ileo-cecal CD and those with UC. Methods This was a multi-center retrospective study including 21 sites affiliated with the Porto IBD group and IBD interest group of ESPGHAN. Data of paediatric patients diagnosed between 2014–2017 with L1 or L2 CD, or with UC, was collected, including information on demographic, clinical and laboratory parameters at diagnosis, end of induction, 1 year and 3 years after diagnosis (or at last follow-up). Results Data was collected on 300 children (102 L1, 94 L2, 104 UC) with similar demographic features. At diagnosis, bloody stools were identified in 45% of L2 patients, compared with 15% and 95% of L1 and UC patients, respectively (P&lt;0.001), while fever was documented in 27% of L2 patients, compared to 13% and 3% of L1 and UC patients, respectively (P&lt;0.001). At the time of diagnosis, the median pediatric Crohn’s disease activity index for patients with L1 and L2 was 25 (IQR 17.5–37) and 27.5 (20–40), respectively, while the median pediatric ulcerative colitis activity index was 40 (30–55) for patients with UC. C-reactive protein levels were significantly higher among CD patients (both L1 and L2), compared to patients with UC, and calprotectin values were comparable. ASCA was positive in 55%, 25% and 2% (P&lt;0.001) and pANCA in 2%, 17% and 53% (P&lt;0.001) in L1, L2 and UC patients, respectively. Granulomas were identified in 36% of L2 patients, similar to patients with L1 (33%). For induction therapy, exclusive enteral nutrition, oral steroids and mesalazine were used in 50%, 45% and 38% of patients with L2 CD, compared with 72%, 28% and 9%, and 0%, 52% and 75% of L1 and UC patients, respectively (P&lt;0.001). Steroid-free clinical remission at the end of induction was overall similar between groups, around 55%. At 1-year post-diagnosis, 62%, 68% and 40% were on an immunomodulator (P=0.03) and 41%, 26% and 22% were receiving anti-TNFα agent (P=0.01), of patients with L1, L2 and UC, respectively. While time to initiation of an anti-TNFα agent was significantly shorter in L1 patients compared with L2 and UC (P=0.03), time to admission and time to surgery were similar. Conclusion Paediatric patients with isolated colonic CD exhibit several clinical features which differentiate them from ileo-cecal CD and UC. Prospective studies are required to understand the pathogenesis of this unique entity and define short- and long-term outcomes.