Inflammatory bowel disease in paediatric rheumatological diseases.

Introduction: Rheumatological diseases (RD) in childhood are systemic diseases that occur on the basis of auto-immunity or inflammation, and they can be accompanied by inflammatory bowel disease (IBD). When there is no knowledge of this association, the treatments applied may not be sufficient and/or treatments given for RD may even lead to aggrevation of IBD findings. Thus, early identification of an association is crucial for the correct management of the diseases.

Objectives: The aim of this study is to show the frequency of IBD in patients with RDs. We also aimed to investigate in which cases IBD should be suspected in children with RDs.

Methods: Electronic medical records of the patients who were followed up between 2012 and 2024 with a diagnosis of RD in our Paediatric Rheumatology Unit and diagnosed with IBD were reviewed retrospectively.

Results: Between 2012 and 2024, 20 (3%) of 650 familial Mediterranean fever (FMF) patients, 3 (7.5%) of 40 chronic nonbacterial osteomyelitis (CNO) patients (one of them also had FMF) and 2 (1.2%) of 170 juvenile idiopathic arthritis (JIA) patients were diagnosed with IBD. While 15 (62.5%) of the patients received a RD as the initial diagnosis, 9 (37.5%) of them were initially diagnosed with IBD and then referred to rheumatology for their symptoms. The median age at the diagnosis of RD was 9 years (inter quartile range (IQR), 14.5). The median age at the diagnosis of IBD was 12 years (IQR, 13), and 12 patients (50%) had Crohn's disease (CD), 10 patients (41.6%) ulcerative colitis (UC) and 2 patients (8.4%) undeterminated disease. Although majority of the patients had classical findings of IBD, 4 patients presented with more vague symptoms including treatment-resistant iron deficiency anaemia, perianal abscess, weight loss and growth retardation.

Conclusions: RD and IBD share similar pathological pathways and clinical findings, and IBD can accompany to various RD. The diagnosis of IBD should be considered in the presence of rare and atypical symptoms. Furthermore, RD should also be considered in children with IBD who have complex extraintestinal symptoms. Key Points • RD, especially FMF, JIA and CNO, may be associated with IBD. • Paediatric rheumatologists should consider IBD as a potential diagnosis in the presence of atypical findings that may develop during the course of RD. • The co-existence of RD and IBD is important both in terms of disease progression and treatment decisions.