Abstract
A 72-year-old man was admitted due to dyspnea on exertion with interstitial shadows and elevated serum creatinine kinase (CK). Despite a close examination, which included magnetic resonance imaging (MRI), we could not diagnose myopathy. Prednisolone was administered and gradually tapered. One year later, anti-signal recognition particle (SRP) antibody was confirmed and he was re-admitted for hypoxemia with elevated CK. MRI revealed muscle edema and a histopathological examination of a muscle biopsy specimen showed necrotizing myopathy. Prednisolone, cyclosporine, and intravenous immunoglobulin were administered. Physicians should carefully monitor muscle symptoms and serum CK levels in cases of interstitial lung disease with anti-SRP antibodies.