New onset of juvenile dermatomyositis after COVID-19 infection in two patients: a case report

Coronavirus disease 2019 (COVID-19) has been linked to the production of various autoantibodies and the development of autoimmune diseases. Severe acute respiratory syndrome coronavirus (SARS-CoV)-2 infection may induce myositis, and several adult cases of dermatomyositis following COVID-19 have been reported. However, reports of juvenile dermatomyositis (JDM) following COVID-19 have been scarce. We herein detail our experience with the management of two patients who developed JDM following COVID-19 infection. Patient 1 was a 4-year-old boy who developed muscle weakness following COVID-19 infection, which progressed to a rash, continuous fever, and muscle weakness severe enough to render him unable to stand or sit independently. He was subsequently diagnosed with JDM complicated by interstitial pneumonia and was treated with methylprednisolone, oral prednisolone, cyclosporine, and cyclophosphamide, which significantly ameliorated his symptoms within 3 months. Patient 2 was a 13-year-old girl who developed progressive muscle weakness following COVID-19 infection. Physical examination revealed proximal muscle weakness and joint contractures, whereas blood tests showed normal creatine kinase levels but slightly elevated aldolase levels. She was subsequently diagnosed with JDM and treated with methylprednisolone and cyclosporine, which significantly reduced her symptoms. These patients highlight the potential link between SARS-CoV-2 infection and the onset of JDM, with the proposed mechanisms including molecular mimicry, bystander activation, and excessive type I interferon production. COVID-19 may act as a trigger for JDM onset, warranting awareness and further investigation into this association.