New-onset Anti-melanoma Differentiation-associated Gene 5 Antibody Positive Clinically Amyopathic Dermatomyositis Following COVID-19.

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2, is a life-threatening respiratory illness that shares clinical similarities with autoimmune diseases, which some patients subsequently develop. We herein report a case of an older Japanese patient who presented with skin rash, relapsing progressive interstitial lung disease, and anti-melanoma differentiation-associated gene 5 (anti-MDA5) antibody seropositivity after COVID-19 infection. Although the patient was elderly, her symptoms improved with the administration of corticosteroids, tacrolimus, and intravenous cyclophosphamide, indicating that this combination may be a viable treatment option for anti-MDA5 antibody-positive pneumonia, which is a complication of COVID-19.