Successful Treatment with Mycophenolate Mofetil in a Patieint with Anti-MDA 5 Antibody-positive Interstitial Lung Disease and Posterior Reversible Encephalopathy Syndrome.

A 59-year-old woman presented with a rash on the top part of her hands and pain in the wrist joint and was diagnosed with dermatomyositis complicated by interstitial pneumonia positive for anti-melanoma differentiation-associated gene 5 (MDA-5) antibody. However, the patient reported a severe headache following treatment with oral prednisolone and tacrolimus. Posterior reversible encephalopathy syndrome (PRES) was diagnosed based on the brain magnetic resonance imaging findings. Tacrolimus was discontinued, and mycophenolate mofetil was instead administered with a favorable outcome. Mycophenolate mofetil should therefore be considered as an alternative treatment for anti-MDA-5-positive interstitial lung disease in cases where calcineurin inhibitors cannot be used.