Fatal pneumomediastinum in dermatomyositis without creatine kinase elevation.

A 41-year-old woman developed fatal pneumomediastinum in the course of dermatomyositis. One characteristic feature of this patient was the relatively mild myositis with slight elevation of serum creatine kinase. In a literature review, some of the patients with dermatomyositis, but not polymyositis, with a very slight elevation of serum creatine kinase tended to develop spontaneous pneumomediastinum during corticosteroid therapy. Since pneumomediastinum is a highly fatal complication in patients with dermatomyositis, only slight elevation of creatine kinase could be a marker for poor prognosis. Thus, mild/minimal myositis in patients with dermatomyositis should be carefully observed irrespective of corticosteroid therapy.