Skin Rash and Interstitial Pneumonia Can Be a Fatal Combination: A Rare Case of Anti-Melanoma Differentiation-Associated Gene 5 (MDA5)-Associated Interstitial Lung Disease.

We report the case of a 62-year-old male patient fully vaccinated for COVID-19, admitted to our emergency room for persistent fever associated with exertional dyspnoea, skin lesions, diffuse myalgias and arthralgias not responsive to broad-spectrum antibiotic and antiviral therapy, who developed a rapidly progressive refractory to treatment interstitial lung disease due to anti-melanoma differentiation-associated gene 5 (MDA5) antibodies, that required mechanical ventilation and ECMO. Here, we highlight the importance of always considering alternative diagnoses, i.e. viral and autoimmune diseases, including anti-MDA5 antibody screening, when dealing with patients with a skin rash, seronegative polyarthralgias and interstitial pneumonia, or acute respiratory distress syndrome of unknown origin. LEARNING POINTS: MDA5-associated dermatomyositis is a rare systemic syndrome associated with rapidly progressive and treatment-refractory interstitial lung disease.The anti-MDA5 antibody is the key biomarker for the diagnosis.Early diagnosis is crucial to promptly start aggressive immunosuppressive therapy with the aims of improving prognosis and reducing mortality. © EFIM 2021.