Ruxolitinib combined with corticosteroids for the successful treatment of kawasaki disease-associated macrophage activation syndrome: a case report.

OBJECTIVE: To explore the diagnostic challenges of Kawasaki disease (KD)-associated macrophage activation syndrome (MAS) and the therapeutic value of ruxolitinib combined with corticosteroids. METHODS: We retrospectively analyzed the clinical data of one pediatric patient with KD-associated MAS and conducted sorting and analysis of relevant published literature. RESULTS: A 14-month-old male infant presented with fever and rash and was diagnosed with severe KD. Despite initial treatment with intravenous immunoglobulin (IVIG) and aspirin, he developed persistent fever, progressive cytopenia, hepatosplenomegaly, hypofibrinogenemia, hyperferritinemia, reduced NK-cell activity, and extremely elevated soluble interleukin-2 receptor (sCD25), fulfilling the HLH-2004 criteria for MAS. He was successfully treated with ruxolitinib plus methylprednisolone, with rapid resolution of fever, recovery of blood counts, and improvement in coagulation and inflammatory markers. CONCLUSIONS: KD-associated MAS is rare but life-threatening. Early recognition of warning signs and prompt initiation of ruxolitinib-based combination therapy can effectively control cytokine storm and improve clinical outcomes.