Spontaneous pneumomediastinum in a dermatomyositis patient with anti‐melanoma differentiation‐associated gene‐5 antibody and interstitial lung disease despite an initial response to immunosuppressant

We report a 24‐year‐old man with anti‐melanoma differentiation‐associated gene‐5 (MDA5) antibody‐positive dermatomyositis (DM) and interstitial lung disease (ILD) who developed spontaneous pneumomediastinum. By comparing serial thoracic high‐resolution computed tomography scans, we demonstrated the distinct time course showing a paradoxical occurrence of pneumomediastinum despite a radiological improvement of ILD. Our case shows that pneumomediastinum in DM can occur regardless of associated ILD and it is a serious complication that should be considered in DM patients presenting with pulmonary manifestations. Cutaneous vasculopathy may be associated with pneumomediastinum and could potentially be a useful indicator of future disease.