Osteonecrosis in patients with juvenile dermatomyositis: is it associated with anti-MDA5 autoantibody?

Abstract

Dear Editor, Data on osteonecrosis (ON) in JDM are limited [1]. It is usually considered as the result of corticosteroid therapy. Herein, we report a case series of five patients among a cohort of 71 patients with JDM who developed severe ON. All of them had anti-MDA5 positive JDM, which suggests that MDA5-positive JDM patients may have predisposing factors for the development of ON. We retrospectively reviewed the cohort of 71 patients with JDM followed in the Paris referral center for Rare Paediatric Rheumatism and systemic autoimmune diseases (RAISE), between December 2010 and December 2021. Inclusion criteria were: (i) diagnosis of JDM, according to Bohan and Peter criteria with a follow-up of at least 2 years; and (ii) ON diagnosed by bone MRI. During the period of inclusion, myositis-specific antibodies (MSA) were searched once for in all the patients by dot-blot immunoassay using Euroline Autoimmune Inflammatory Myopathies 16 Ag (Euroimmun) and Blue Diver PMS12-24 (D-Tek). IFN-α2 protein concentration was measured by SIMOA assay (Quanterix Homebrew). All statistical analyses were performed using GraphPad Prism (version 9.1.1). After parental consent, patients were registered in the French rare diseases National database (BAMARA). This study was approved by the Ethics board of Necker hospital.