The Serum Ferritin Level Is Associated with the Treatment Responsivity for Rapidly Progressive Interstitial Lung Disease with Amyopathic Dermatomyositis, Irrespective of the Anti-MDA5 Antibody Level.

We report the case of a 61-year-old woman with rapidly progressive interstitial lung disease caused by clinically amyopathic dermatomyositis. Both the serum ferritin and anti-melanoma differentiation-associated gene 5 (MDA5) antibody levels were elevated at the time of admission. Despite intensive treatment with corticosteroids, immunosuppressants, immunoglobulins and polymyxin B direct hemoperfusion, the patient died 75 days after symptom onset. Over the course of treatment, the anti-MDA5 antibody level continually decreased, while the serum ferritin level increased, suggesting that sequential measurements of the serum ferritin level might be useful for evaluating the treatment responsivity, irrespective of the anti-MDA5 antibody level.