Lung involvement in juvenile idiopathic inflammatory myopathy: A systematic review

Objective: Juvenile idiopathic inflammatory myopathies (JIIM) are a group of connective tissue disorders characterized by muscle inflammation and variable systemic involvement, including interstitial lung disease (ILD). Available data on JIIM-associated ILD are very limited. We performed a systematic review of the available clinical, laboratory, and radiological features of JIIM-associated ILD. Methods: A systematic literature review was performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.Results: A total of 90 patients were identified, of whom 77.8% had JDM, 10% amyopathic JDM, 7.8% antisynthetase syndrome, 3.3% overlap syndrome, and 1.1% juvenile polymyositis. Anti-melanoma differentiation-associated gene 5 (MDA-5/CADM-140) was the most frequently reported myositis-specific antibody (32.2%). At diagnosis of ILD, 55.5% of patients had respiratory symptoms. Ground glass opacity was the most reported radiological feature (52.9%). Thirty-three % of patients developed rapidly progressive (RP) lung disease; 26.7% were admitted to the intensive care unit (ICU); 28.9% died; all deaths were due to ILD, with a median interval of 2 months (IQR 1.5-4.7) between the onset of respiratory symptoms and death. Patients admitted to the ICU and who died of ILD were more likely to be male, to have a rapidly progressive pattern, progression of radiological features, and a higher level of KL-6.Conclusions: MDA-5/CADM-14 is associated with RP-ILD. ILD is a rare but severe manifestation among the spectrum of systemic involvement associated with JIIM, with a high rate of ICU admission and mortality. Early recognition and aggressive treatment are needed to prevent a severe outcome.