Fatal Rapidly Progressive Interstitial Lung Disease in Anti-Melanoma Differentiation-Associated Gene 5 (MDA5) Dermatomyositis in a Brazilian Patient: A Case Report

Anti-melanoma differentiation-associated gene 5 (anti-MDA5) dermatomyositis (DM) is a subtype of idiopathic inflammatory myopathy. It is characterized by prominent cutaneous manifestations, minimal muscle involvement, and a strong association with interstitial lung disease (ILD), particularly rapidly progressive ILD (RP-ILD), a life-threatening complication with high early mortality. Although RP-ILD is less frequently reported in Western populations than in Asian cohorts, severe presentations may still occur. We report the case of a previously healthy 35-year-old woman who presented with typical DM features and progressive dyspnea. Chest computed tomography (CT) revealed an organizing pneumonia pattern consistent with ILD. Despite early aggressive immunosuppression, the patient developed pneumomediastinum, pneumothorax, and worsening diffuse ground-glass opacities. Anti-MDA5 positivity was confirmed, and even after rescue therapy and intensive supportive care, the patient died. This case illustrates the fulminant course of anti-MDA5 DM with RP-ILD and severe structural complications, emphasizing the need for early recognition and aggressive immunosuppression even in populations with a lower reported prevalence of RP-ILD.