Background: Adult-onset Still's disease (AOSD) is a rare inflammatory disorder that typically presents with high spiking fevers, arthralgia, and a transient skin rash. Atypical manifestations such as anasarca and multiorgan involvement are infrequent but clinically significant.
Case Presentation: We report the case of a 29-year-old South Asian male who presented with high-grade intermittent fevers, anasarca, pleural and pericardial effusions, hepatosplenomegaly, and marked hyperferritinemia. Despite exhaustive workup, no infectious, autoimmune, or neoplastic cause was found. The patient responded favorably to corticosteroids and tocilizumab, confirming the diagnosis of AOSD.
Conclusion: This case highlights the diagnostic challenges of atypical AOSD presentations and underscores the importance of considering AOSD in patients with prolonged fever of unknown origin and hyperferritinemia.