COPA and interstitial lung disease specific to childhood: In this study we focused on the efficacy and safety of hydroxychloroquine (HCQ) in patients with chILD and a lung histology pattern of chronic pneumonitis of infancy, non-specific interstitial pneumonitis (NSIP), desquamative interstitial pneumonitis, microscopic alveolar proteinosis or cholesterol pneumonitis, pulmonary hemosiderosis, follicular bronchiolitis and lymphocytic interstitial pneumonitis, as well as on chILD caused by mutations in SFTPC, ABCA3, NKX2.1, TBX4, or COPA.