Interstitial lung diseases associated with amyopathic dermatomyositis

The aim of the present study was to clarify the clinical characteristics and prognosis of patients with interstitial lung disease (ILD) associated with amyopathic dermatomyositis (ILD-ADM). The study consisted of 14 consecutive patients with ILD-ADM. Patients were classified into two categories, acute/subacute and chronic forms, according to the clinical presentation of ILD. The clinical features, responsiveness to therapy, and prognosis between the two forms were compared. Nine ILD-ADM patients were categorised as the acute/subacute form, and five as the chronic form. Arterial oxygen tension was significantly lower in the acute/subacute ILD than chronic ILD patients. On high-resolution computed tomography, ground-glass opacities were frequently found in the two forms, but consolidation was more common in acute/subacute ILD than chronic ILD. Bronchoalveolar lavage analysis showed higher numbers of total cells and lymphocytes in acute/subacute ILD than chronic ILD. Histologically, the most common finding was nonspecific interstitial pneumonia in the two forms, while diffuse alveolar damage was only found in acute/ subacute ILD. Acute/subacute ILD was generally resistant to therapy, while chronic ILD responded well. Notably, the mortality of acute/subacute ILD was much higher than that of chronic ILD (67 versus 0%, respectively). In conclusion, interstitial lung disease associated with amyopathic dermatomyositis includes two different forms, the acute/subacute and chronic forms, with distinct prognoses.