Case Report: Treatment of refractory lung disease in systemic juvenile idiopathic arthritis with cyclophosphamide and rituximab combination therapy

IntroductionSystemic juvenile idiopathic arthritis-associated lung disease (sJIA-LD) is a rare, potentially fatal complication of sJIA, often accompanied by pulmonary hypertension (PHTN) and macrophage activation syndrome (MAS). The underlying pathophysiology remains poorly understood and optimal management strategies have yet to be established.

Recent retrospective data suggest that combination therapy with cyclophosphamide (CYC) and rituximab (RTX) may be effective in children with severe or life-threatening manifestations of rheumatic disease. Yet, literature on combination therapy in sJIA-LD is lacking.MethodsWe describe two pediatric cases of sJIA-LD complicated by PHTN and recurrent episodes of MAS.

Both patients remained refractory to conventional sJIA therapies, necessitating escalation with combination CYC–RTX.ResultsFollowing combination CYC–RTX therapy, both patients demonstrated marked clinical improvement, including resolution of hyperferritinemia, normalization of acute phase reactants, and recovery of hepatic function profiles. Patient 1 experienced a reduction in supplemental oxygen requirement from 4 liters per minute (LPM) to 0.5 LPM nocturnally as well as improved PHTN measures: mean pulmonary arterial pressure decreased from 47 to 25 mmHg, and pulmonary vascular resistance decreased from 11.1 to 4.3 Wood units.