First-Line Tocilizumab Monotherapy for Juvenile Systemic Sclerosis With Interstitial Lung Disease: A Case Report.

Systemic sclerosis, a rare autoimmune disease in children, frequently presents with aggressive clinical features and high risk of interstitial lung disease. Tocilizumab, an anti-interleukin-6 receptor monoclonal antibody, has exhibited efficacy in adult systemic sclerosis with interstitial lung disease; however, evidence in pediatric cases remains extremely limited. We report a 12-year-old Japanese girl who developed early-stage juvenile systemic sclerosis with interstitial lung disease, presenting with Raynaud's phenomenon, puffy fingers, positive anti-topoisomerase I antibody, reduced pulmonary function, and ground-glass opacities on high-resolution computed tomography. Consequently, tocilizumab monotherapy was initiated. During a follow-up period of over 3 years, her pulmonary function remained stable, and high-resolution computed tomography showed partial resolution of interstitial changes. No significant adverse events, such as severe infections or cytopenias, were observed. Early tocilizumab initiation may represent a potential therapeutic option for juvenile systemic sclerosis with interstitial lung disease. However, further studies are warranted to validate its role and optimize treatment guidelines for this rare but severe condition.