An Atypical Clinical Course of Anti-MDA5 Antibody-positive Interstitial Lung Disease in a Patient with Three Deteriorations in 9 years

Anti-MDA5 antibody-positive patients with clinically amyopathic dermatomyositis (CADM) are at high risk of developing rapidly progressive interstitial lung disease (ILD), which is associated with a high mortality rate. Approximately half of the patients with ILD recover; however, the long-term clinical course of these patients has not been fully reported and is not completely understood. This report describes the atypical clinical course of an anti-MDA5 antibody-positive CADM patient who experienced three deteriorations of ILD in 9 years. These findings indicate that the ILD in anti-MDA5 antibody-positive patients may not only be rapidly progressive, but may also be chronic and recurrent.