Prolonged Fever in a Pediatric Patient: A Case of Systemic Juvenile Idiopathic Arthritis (sJIA) Complicated by Macrophage Activation Syndrome (MAS)

A prolonged fever in a child can be due to a range of causes including infectious, autoimmune, malignant, or genetic in etiology. In our report, we present the case of a previously healthy three-year-old female diagnosed with macrophage activation syndrome (MAS) due to complications of systemic juvenile arthritis (sJIA). MAS is considered a secondary subtype of hemophagocytic lymphohistiocytosis (HLH), a rare and life-threatening group of syndromes characterized by overstimulation of the immune system leading to systemic inflammation. Through our case, we wanted to bring awareness to this uncommon group of diseases as well as discuss the importance of differentiating between its subtypes. While HLH and MAS have similar clinical presentations, the treatment regimen for each is distinct. Moreover, further research should be conducted to create standardized criteria and treatment guidelines that are evidence-based in order to properly manage these patients.