Efficacy of plasma exchange for rapidly progressive interstitial lung disease caused by anti-MDA5 antibody-positive dermatomyositis: Report of a case showing resistance to combined immunosuppressive treatment

A 54-year-old male had presented with shortness of breath two months prior to admission. At that time, he was diagnosed with pneumonia, and treated with antibiotics in another facility, but since he showed the progression of interstitial pneumonia, he was referred to our hospital. We diagnosed him with rapidly progressive interstitial lung disease due to anti-MDA5 antibody-positive dermatomyositis (RP-ILD) because he had eruptions such as Gottron’s sign, and anti-MDA5 antibody was positive. He was subsequently admitted to our hospital, and started multiple immunosuppressive therapy including high-dose glucocorticoid (1 mg/kg/day), tofacitinib, and IVCY. Despite such treatment, the interstitial lung disease progressed, and hyperferritinemia persisted. On day 60, we started plasma exchange, leading to significant improvements in the respiratory status, inflammatory data, and radiological findings of interstitial pneumonia. According to previous reports, about 20-30％ of patients do not survive despite multiple immunosuppressive therapy. Regarding such patients, some case reports indicated the effectiveness of plasma exchange. Also, since the pandemic of SARS-CoV-2, the number of RP-ILD patients with anti-MDA5 antibody positivity has reportedly increased. We will report the details of this patient’s clinical course and review the effectiveness of plasma exchange in cases of resistance to combined immunosuppressive treatment for rapidly progressive interstitial lung disease caused by anti-MDA5 antibody-positive dermatomyositis.