Idiopathic inflammatory myopathy with diffuse alveolar damage.

Interstitial lung disease (ILD) in patients with myositis is defined by the presence of interstitial changes on radiographic examination. The reported prevalence of ILD varies from 0% to nearly 50%. However, only rarely has the pathological pattern of diffuse alveolar damage (DAD) associated with idiopathic inflammatory myopathy (IIM) been reported. We report five patients with IIM (one with dermatomyositis, one with polymyositis, and three with amyopathic dermatomyositis) and respiratory failure. Four underwent open lung biopsy with pathological proof of diffuse alveolar damage (DAD). Despite intensive immunosuppressive therapy, all of them died. In addition to the case reports, we discuss DAD in patients with IIM.