Adult and juvenile-onset inflammatory myopathy: autoantibodies and muscle MRI in a cohort of Egyptian patients

Abstract Background Idiopathic inflammatory myopathies are a group of autoimmune conditions primarily affecting the proximal muscles and can involve other organs, such as the skin, joints, and lungs. Many diagnostic and classification criteria have been suggested for myositis depending on the clinical picture, laboratory investigations, electromyography, muscle biopsy and, recently, myositis-specific antibodies, in our cross-sectional observational study we analyzed data of a cohort of 77 patients all of whom presented with clinical manifestations indicative of myositis. The investigations involved the detection of 17 myositis autoantibodies, aiming to detect the presence of those autoantibodies in a sample of adult and juvenile-onset myositis Egyptian patients. Additionally, whole-body muscle magnetic resonance imaging (MRI), encompassing T1, T2 and STIR (short-tau inversion recovery) sequences, was performed. Results A total of 34 (44%) patients, comprising 23 adults and 11 juvenile-onset patients, exhibited positive results for myositis autoantibodies. In the adult group, dermatomyositis emerged as the predominant subtype, with a notable female sex predominance. In the juvenile group, overlap myositis was the most common antibody subtype, with a predominance of males. Detailed presentations of the clinical features, laboratory results, and MRI findings were obtained for both the adult and juvenile age groups. Conclusion Autoantibodies and MRI of muscles are important tools for the diagnosis of myositis subtypes in all patients with inflammatory myopathy, which paves the way for accurate diagnoses and therapies.