Anti-MDA5 Associated Clinically Amyopathic Dermatomyositis With Rapidly Progressive Interstitial Lung Disease

Anti-melanoma differentiation-associated protein 5 (anti-MDA5) associated clinically amyopathic dermatomyositis (CADM) is a rare entity that is frequently associated with rapidly progressive interstitial lung disease. The disease is characterized by its association with a distinct myositis specific antibody, the lack of muscle involvement seen with other inflammatory myopathies, and a strong correlation with the development of rapidly progressive interstitial lung disease. Diagnosis is based on clinical findings and the presence of autoantibodies. Management generally involves combination immunosuppression therapy. However, the disease course is often aggressive and lends a poor prognosis. We report a case of a healthy 55-year-old male who presented with dyspnea, dry cough, and joint pain for 1 month. The patient was diagnosed with anti-MDA5 associated CADM with interstitial lung disease after a complete rheumatological workup found elevated titers of MDA5 antibodies and computed tomography of the chest without contrast revealed radiographic evidence of interstitial lung involvement. Disease course was complicated by the development of Pneumocystis pneumonia as a result of profound immunosuppression from combination immunosuppressant therapy. Our patient eventually succumbed to his illness approximately 10 weeks following initial symptom onset. This case highlights the aggressive nature of the disease and the challenges in management. Further research is warranted to establish more effective therapeutic options.