Herein, we present a case of a 3-year-old girl patient with anti-MDA5-positive JDM complicated by RP-ILD, whose lung condition continued to worsen on imaging despite receiving multiple immunosuppressive intensive therapies, including intravenous immunoglobulin (IVIG), glucocorticoid, tofacitinib, tacrolimus, and cyclophosphamide. The gene discussed is IFIH1; the disease is interstitial lung disease.