SAT0488 THE FRENCH PAEDIATRIC COHORT OF CASTLEMAN DISEASE

Background: Castleman disease (CD) is a very rare non-malignant lymphoproliferation of undetermined origin. CD diagnosis is difficult and often delayed because of insidious onset, low awareness and clinical heterogeneity. Two major disease phenotypes can be distinguished: unicentric CD (UCD) and multicentric CD (MCD). Diagnosis confirmation is based on histopathological findings on an involved lymph node. Objectives: We attempted to survey all cases of paediatric CD identified in France so far, in order to set up a national registry aimed to improve CD early recognition, treatment and follow-up, within the context of a new reference centre (http://www.castleman.fr). Methods: In 2016, we e-mailed a questionnaire to members of the French paediatric immunohaematology society, the French paediatric rheumatology society and the French Reference Centre for Castleman Disease to retrospectively collect cases of paediatric CD (first symptoms before age 18 years). Anatomopathological confirmation was mandatory. Results: We identified 23 patients (12 girls and 11 boys) diagnosed with UCD (n=17) and MCD (n=6) between 1994 and 2018 in 14 centres. The average age at first symptoms was 11.5 years for UCD and 8.3 years for MCD. The mean diagnosis delay was 8.2 months for UCD and 5.2 years for MCD. In UCD, the initial symptoms were: isolated lymph nodes (n = 10) or lymph node associated with other symptoms (n = 7), fever was present in 3 patients. Patients with MCD presented with fever (n=5), abdominal lymph nodes (n=5), failure to thrive (n=3), hepatomegaly and/or splenomegaly (n=3), arthralgia (n=2), abdominal pain (n=2), fatigue (n=2), facial oedema (n=1), isolated lymphadenopathy (n=1), trunk rash (n=1), vascular hepatopathy with oesophageal varicose veins (n=1), diarrhea (n=1) or cholestasis (n=1). One patient had a Duchenne muscular dystrophy. No patients had HIV or HHV8 infection. In MCD cases, one patient with recurrent fevers, had a heterozygous mutation in MEFV gene and another had a homozygous mutation in TNFRSF1A gene (P75L). A UCD patient experienced fever episodes and pericarditis two years after surgery. Genetic tests revealed one heterozygous mutation in IL10RA gene (V406L) and one in IL36RN gene (S113L). Nevertheless, our patient did not have any psoriasis or inflammatory bowel disease. Treatment of UCD was mainly surgical resection, steroids, and radiotherapy. Treatments of MCD were tocilizumab, rituximab, anakinra, steroids, chemotherapy and splenectomy. Overall survival after an average of 6 years of follow-up, was 100% for both unicentric and multicentric forms. Conclusion: Paediatric CD seems still underdiagnosed with a significant diagnosis delay specially for the MCD but new international criteria will help in future. In UCD, surgery is the main treatment. New drugs are used specially for the MCD, but more studies need to be conduct in children. The global survey is better in children than adults. Disclosure of Interests: Charlotte Borocco: None declared, Claire Ballot-Schmit: None declared, Oanez Ackermann: None declared, Nathalie Aladjidi: None declared, Jeremie Delaleu: None declared, Vannina Giacobbi-Milet: None declared, Sarah Jannier: None declared, Eric Jeziorski: None declared, Yves Perel: None declared, Francois Maurier: None declared, Christophe Piguet: None declared, Eric Oksenhendler: None declared, Isabelle Kone-Paut Grant/research support from: SOBI has supported drug product (anakinra) for the presented study, Consultant for: SOBI, Novartis, Pfizer, Abbvie, UCB, CHUGAI, ROCHE, Caroline Galeotti: None declared