Introduction: Spontaneous pneumomediastinum is a rare complication of dermatomyositis.
Case report: We report a case of pneumomediastinum with massive subcutaneous emphysema occurring in a female patient with dermatomyositis treated with cortico-steroids.
Conclusions: Our case illustrates perfectly the mechanism of spread of air along the broncho-vascular structures and also explains the presence of pneumomediastinum in the absence of pneumothorax.