High-resolution computed tomography characterization of interstitial lung diseases in polymyositis/dermatomyositis

Interstitial lung disease (ILD) associated with polymyositis (PM) and dermatomyositis (DM) sometimes progresses rapidly and is resistant to therapy. Clinical features that forecast the prognosis of the disease remain to be elucidated. Our aim was to assess if selected clinical features and high-resolution computed tomography (HRCT) findings can assist in predicting the clinical course of ILD in PM/DM.

We examined HRCT findings retrospectively for ILD identified in 17 patients with PM and 16 with DM. Radiological patterns and clinical features are analyzed in comparison with clinical course.

Mortality rates were 12% and 44% for ILD associated with PM and DM, respectively. Most patients with DM died of rapidly progressive lung deterioration. No patient in the PM group died of respiratory failure. In the DM group, all patients with fatal ILD had ground-glass attenuation and reticular opacity as the principal radiological findings. Consolidation was recognized frequently as the principal pattern in nonfatal cases. Radiological patterns were categorized into 3 groups; A: consolidation dominant, B: ground-glass attenuation/reticular opacity dominant without chronic fibrosing process, and C: ground-glass attenuation/reticular opacity dominant with chronic fibrosing process. Occurrences of fatal disease were 0%, 83%, and 20%, in groups A, B, and C.

The prognosis of ILD associated with DM differs from that with PM. The former can be classified into 3 subgroups on the basis of radiological findings, which are closely associated with clinical course.