Background/Purpose: Still’s Disease (SD)-associated lung disease (SD-LD) is a severe potentially life-threatening condition characterized by peculiar features. For the rarity of this condition, the experience on the management of SD-LD patients is limited.

Methods: We report clinical data and treatment strategies of 9 SD-LD patients followed in a single tertiary paediatric rheumatology centre in Italy.

Results: Nine White-Caucasian patients with SD-LD diagnosed between 2017 to 2025 are followed in our division. The median age at SD onset was 1.3 years (range 4 months – 13.4 years) and at LD onset was 2.4 years. None of our patients had trisomy 21.
Eight out of 9 patients (88%) had history of MAS with recurrent episodes in 6 of them (75%).
Seven (77%) patients carried the HLA-DRB1*15 haplotype and 8 (88%) carried the HLA-DRB1*11 haplotype. IL-18 levels were persistently elevated with a median value at time of LD onset of 320,000 pg/ml (range 74,564 – 515,100 pg/ml). Six (66%) out of 9 patients had eosinophils count higher than 1.000 mmc in at least two occasions during disease course.
Eights patients were exposed to IL-1 inhibitors before LD diagnosis, 5 to anakinra and 3 to both anakinra and canakinumab. Six patients had drug reaction to IL-1 or IL-6 inhibitors, 2 to anakinra and 4 to tocilizumab. The 2 patients who reacted to anakinra presented the drug reaction before the onset of LD while the reaction to tocilizumab occurred after the onset of LD in all 4 patients. The only patient who did not receive IL-1/IL-6 inhibitors before LD diagnosis, developed the most severe lung involvement despite several treatments.
After LD diagnosis, 6 patients received intravenous glucocorticoids; IL-1 and IL-6 inhibitors were variably used in addition to other immunomodulatory treatments, anakinra was used in 4 patients, canakinumab in 5 and tocilizumab in 3. All the patients received cyclosporine as T cell immunosuppressant; in addition to mycophenolate mofetil in 4 patients and to sirolimus in 1. Targeted therapies were also used in addition to other treatments, ruxolitinib was administrated in 6 patients, emapalumab in 3 patients and MAS825 in 4. The response to treatment was quite heterogeneous. SD-LD improved in 4 patients, 3 on Ruxolitinib and 1 on MAS825, remained stable in 3 patients and worsened in 2. The patient with the most severe lung involvement, who progressed while on treatment (ruxolitinib, MAS825 and emapalumab), received haematopoietic stem cell transplantation. None of the 9 patients developed LD complications, none required O2 supplementation. Only 1 patient was admitted in ICU for severe infection.
All 9 patients are alive at last follow-up (median follow-up for LD of 3 years and 4 months, range 5 months-8 years) with SD in clinical inactive disease on medication.

Conclusion: Patients with SD-LD had highly variable disease course. Treatment strategies are very heterogeneous.  Multicentre studies are needed to define management guidelines and to identify the best treatment strategies.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/stills-disease-associated-lung-disease-experience-from-a-tertiary-italian-centre/