Efficacy of combined JAK1/2 inhibition and cyclosporine in paediatric-onset Still’s disease with lung involvement: a case report

Paediatric-onset Still’s disease is a severe autoinflammatory disorder marked by high fever, systemic inflammation, rash, organomegaly, and arthritis. Pulmonary complications, once anecdotally reported, have been increasingly observed in paediatric Still’s disease. A more severe lung involvement, Still-associated lung disease, has emerged in the last ten years, including interstitial lung disease, pulmonary hypertension, and pulmonary alveolar proteinosis (PAP). This complication carries significant morbidity and mortality. Its mechanism remains poorly understood; current biologic therapies targeting interleukin (IL)-1 and IL-6 often prove insufficient, supporting the need for innovative approaches or combined treatment. A 10-year-old girl with Still’s disease developed PAP and pulmonary hypertension. After several treatment failures and ongoing oxygen dependency, she responded favourably to a combination of baricitinib and cyclosporine. This allowed for gradual corticosteroid tapering and eventual discontinuation, achieving sustained disease control without further oxygen supplementation. Pulmonary assessment, echocardiography, cardiac catheterization, bronchoalveolar lavage, and lung biopsy were performed, along with immunological profiling, HLA typing, and genetic analysis. The type I IFN signature was closely monitored, with normalization observed after reaching the therapeutic dose of baricitinib. This case provides evidence of the long-term efficacy and safety of baricitinib combined with cyclosporine in managing Still-LD, offering a promising option for this severe complication.