In this episode, Dr. Randy Q. Cron discusses hyperinflammation and Macrophage Activation Syndrome (MAS), one of the most serious complications of Still's disease. Because MAS can mimic infection, sepsis, malignancy, or a disease flare, early recognition is critical—and treatment often must begin before every diagnostic criterion is met. We explore the clinical patterns and laboratory findings that matter most, how to interpret ferritin, and how to make timely decisions when multiple diagnoses may exist at once.