Case Report: Delayed diagnosis of adult-onset Still’s disease after sepsis-like acute liver failure with macrophage activation syndrome

BackgroundAdult-onset Still's disease (AOSD) is a rare systemic autoinflammatory disease characterized by heterogeneous and nonspecific clinical manifestations. It often requires differentiation from infectious diseases, malignancies, and other rheumatic autoimmune disorders, making early diagnosis challenging. Acute liver failure (ALF) is a rare but severe complication of AOSD. AOSD may also be complicated by macrophage activation syndrome (MAS), a severe hyperinflammatory condition that can cause multiorgan dysfunction and mimic sepsis, further complicating diagnosis and management.Case presentationWe report a 35-year-old woman with AOSD complicated by macrophage activation syndrome who initially presented with acute liver failure. Multiple pathogens were detected by metagenomic next-generation sequencing (mNGS), leading to an initial misdiagnosis of sepsis. Over the following two years, the patient experienced recurrent episodes of fever, rash, arthralgia, and liver dysfunction. After comprehensive evaluation, the diagnosis of AOSD was established according to the Yamaguchi criteria, and MAS was diagnosed based on the HLH-2004 criteria and HScore. The patient achieved clinical remission after high-dose glucocorticoid therapy and remained stable during follow-up.ConclusionsThis case highlights that AOSD complicated by MAS should be considered in patients with unexplained fever and acute liver failure, particularly those with hyperferritinemia, rash, and multisystem involvement. Even in the presence of evidence suggestive of infection, clinicians should remain vigilant for AOSD with MAS to avoid misdiagnosis and delayed treatment.