A 14-Year-Old Female With Several-Week History of Rash, Worsening Diffuse Arthralgias, and Fevers

Macrophage activation syndrome (MAS) as the initial presentation of systemic juvenile idiopathic arthritis (sJIA) is an uncommon and difficult diagnosis to ascertain. However, it remains critical to establish the diagnosis since MAS is a potentially life-threatening systemic inflammatory condition. Prompt recognition can lead to early initiation of treatment with corticosteroids and overall improved outcomes. Here, we present a case of a 14-year-old female with MAS as the initial manifestation of sJIA.