Case Report: Spontaneous pneumomediastinum in a patient with MDA5-positive dermatomyositis and severe pulmonary fibrosis.

Introduction: Dermatomyositis (DM) is a rare autoimmune disorder, with the anti-melanoma differentiation-associated gene 5 (anti-MDA5) antibody positive subtype associated with severe complications such as rapidly progressive interstitial lung disease (RP-ILD) and, more rarely, spontaneous pneumomediastinum (SPM). This case highlights the challenges of managing a patient with such complex condition, particularly in the context of multiple comorbidities, including a history of cancer and recurrent infections. Case description: A 45-year-old woman with an history of vulvar squamous cell carcinoma (July 2022) presented with classic features of DM, including Gottron's papules, proximal muscle weakness, dysphagia, severe cutaneous vasculitis and lymphopenia. She was then diagnosed with anti-MDA5-positive DM in October 2023. High-resolution CT (HRCT) of the lung performed in January 2024, in the absence of respiratory symptoms, revealed early interstitial changes with ground-glass opacities. Initial corticosteroid therapy yielded partial improvement. A Conclusion: This case emphasizes the complexity of managing anti-MDA5-positive DM with severe pulmonary complications. Early recognition, a multidisciplinary approach, and personalized treatment are crucial to improving outcomes.