P383 Chronic Recurrent Multifocal Osteomyelitis associated with Paediatric Inflammatory Bowel disease: A Multi-Center Retrospective Study from the Paediatric IBD Porto Group of ESPGHAN
Authors: Matar M , Cebecauerova D , Kolho K L , Scarallo L , Hussey S , Yerushalmy-Feler A , Pujol-Muncunill G , Rolandsdotter H , Distante M , Granot M , Olbjørn C , Zetterström C K , Velasco Rodríguez-Belvís M , de Laffolie J , Ledder O , Van Biervliet S , Navas-López V M , Van Limbergen J , Konidar A , Shamir R , Shouval D S 
Published: January 2024

Abstract

Background
Chronic Recurrent Multifocal Osteomyelitis (CRMO) is a rare, autoinflammatory bone disorder. CRMO was linked with inflammatory bowel disease (IBD), either as an extra intestinal manifestation or as a paradoxical effect of anti-TNFa therapy. Our goal was to define the clinical features and natural history of patients carrying a dual diagnosis of CRMO and IBD

Methods
Medical records of pediatric patients with a dual diagnosis of IBD and CRMO were reviewed in nineteen centers from the Paediatric IBD Porto Group of ESPGHAN. Collected data included demographic characteristics, disease features, laboratory studies, bone imaging findings and outcomes of each disease

Results
Forty five patients (21 [47%] females) with a diagnosis of CRMO and IBD (32 [71%] with Crohn’s disease) were included. Median age at the time of dual diagnosis was was 10.2 (IQR 12-13.5) years. Patients were divided into 3 groups, based on whether CRMO developed before, during or after IBD diagnosis. In 15 patients (33%), CRMO was diagnosed ±3 months from the time of IBD diagnosis, with 8 (53%) and 2 (13%) exhibiting mild and moderate-severe IBD activity, respectively. In 20 children (44%) IBD preceded CRMO diagnosis by &gt;3 months with a median time of 238 (85-344) weeks. At the time of dual diagnosis, 12 (60%) patients were in IBD remission and 5 (25%) exhibited moderate-severe disease activity; however, CRP and ESR were elevated (1.5 [0.4-3.4] mg/dL and 35 [21-55] mm/h, respectively) while median fecal calprotectin was 567 (68-1800) mcg/gr, including 4 patients &lt;100 mcg/gr. 17 patients (85%) were on anti-TNFa medication at the time CRMO developed. In 10 (22%) patients CRMO preceded the diagnosis of IBD (&gt;3 months before IBD evolution) with a median time 46 (25-248) weeks. At time of IBD presentation, CRMO was in remission in 5 patients (50%). 4 patients were diagnosed with IBD, despite the lack of any abnormal gastro-intestinal symptoms. In patients in which CRMO was diagnosed after or during IBD diagnosis, different therapeutic regimens were used, including anti-TNFa agents, methotrexate, ustekinumab, NSAID’s and corticosteroids. Two patients also received bisphosphonates. In patients in which CRMO was diagnosed after or during IBD diagnosis, CRMO remission, defined as lack of bone pain, was achieved in 22.2 (15-51.8) weeks. CRMO complications occurred in 4 patients and included vertebral collapse, length discrepancy, bone fracture and bone deformity

Conclusion
In the largest cohort to date, CRMO presentation was not necessarily related to clinically active intestinal inflammation and could present before, during or after IBD diagnosis. CRMO remission was achieved in all patients; Nevertheless, a small number of patients developed significant bone complications