[A case of dermatomyositis associated with asymptomatic pneumomediastinum]

A 20-year-old woman initially presented with edematous erythema in the upper eyelids in December 1995. She was admitted to our department in January 1996 because of fever and multiple arthralgia. She was given a diagnosis of dermatomyositis (DM) on the basis of characteristic eruption, elevated serum level of creatine kinase, and increased inflammatory reaction. Chest computed tomography (CT) revealed faint interstitial changes in the left lower lung. The administration of corticosteroid caused improvement in the patient's condition and the interstitial lesion in the lung. Although she was asymptomatic, chest CT showed pneumomediastinum in the pretracheal space and concomitant pneumothorax around left bronchus. Those changes spontaneously disappeared 4 weeks later without treatment. The occurrence of pneumomediastinum in patients with DM has been well documented as an indicator of poor prognosis in the literature. It seems that a severe pulmonary disorder could secondary cause pneumomediastinum. In our case, however, the pneumomediastinum developed in spite of the low grade severity of the pulmonary lesion. This finding suggested that the pneumomediastinum may be associated with the development of DM itself.