LAUSR

Abstract Rationale: Ustekinumab is effective in the treatment of adult Crohn disease (CD) and ulcerative colitis (UC). However, data on its efficacy and safety in pediatric CD and UC are limited. To the best of our knowledge, there are no reports of Japanese children with UC treated with ustekinumab in the long-term. Patient concerns: A 14-year-old man with diarrhea and bloody stools was referred to our hospital. Colonoscopy revealed total colitis-type UC. His pediatric UC activity index score was 50, indicating moderately active UC. Diagnoses: Ulcerative colitis. Interventions: Infliximab was introduced because of steroid-resistant refractory UC; however, secondary ineffectiveness was observed 17 months later. Therefore, ustekinumab was administered along with prednisolone (16 years of age). Outcomes: The patient achieved UC remission after ustekinumab treatment, leading to maintained remission without side effects. Lessons: To the best of our knowledge, this is the first pediatric case of moderately active UC successfully treated with ustekinumab in Japan. Ustekinumab combined with steroids is an effective and safe induction therapy for UC.