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.