Clinical analysis and outcome of interstitial lung disease complicated with juvenile dermatomyositis and juvenile polymyositis.

Objectives: The aim of this study was to determine the clinical phenotype and outcome of interstitial lung disease (ILD) complicated with juvenile dermatomyositis (JDM) or juvenile polymyositis (JPM).

Methods: This was a single-center retrospective study. From 1984 to 2015, we retrospectively reviewed 29 patients who were diagnosed with JDM/JPM, among whom eight cases were ILD and 21 were non-ILD. The clinical features and laboratory findings included chest computed tomography (CT) images that were compared between the patients with ILD and non-ILD.

Results: Eight cases (27.6%) were complicated with ILD. The mean age was 6.3 years, and 75% of the patients were women. We found that high fever, arthralgia, muscle weakness, and high serum Krebs von den Lungen-6 (KL-6) level were significantly associated with the presence of ILD (p < 0.05). Two patients were positive for the anti-Jo-1 antibody, and two other patients were positive for the anti-MDA5 antibody. Three cases were identified as rapidly progressive (RP)-ILD. The chest CT images of the ILD patients appeared to show ground glass opacity (GGO) with a lower lobe predominance, reticulation, and traction bronchiectasis consolidation. Three patients with RP-ILD showed random subpleural GGO with/without consolidation patterns. Further, three patients with RP-ILD died of respiratory failure (p < 0.01).

Conclusion: ILD is one of the most serious complications of JDM/JPM. In the early phase of ILD, high levels of serum KL-6 can be detected, regardless of the respiratory symptoms. Additionally, RP-ILD can be predicted based on the presence of anti-MDA5 antibodies and the chest CT findings, including random subpleural GGO with/without consolidation patterns.