A case of anti-MDA5-positive rapidly progressive interstitial lung disease in a patient with clinically amyopathic dermatomyositis ameliorated by rituximab, in addition to standard immunosuppressive treatment.

Rapidly progressive interstitial lung disease (RP-ILD) in patients with clinically amyopathic dermatomyositis (CADM) associated with antibodies to melanoma differentiation-associated gene5 (MDA5) results in a high mortality rate. We experienced a case of anti-MDA5-positive RP-ILD of CADM which showed a response to rituximab, although there was no significant effect due to standard immunosuppressive treatment. This case suggests that rituximab has the potential to offer an effective agent for the treatment of anti-MDA5-positive RP-ILD of CADM.