New Onset Autoimmune Disease or Macrophage Activation Syndrome?

Macrophage activation syndrome (MAS) is a potentially life-threatening condition that may complicate many pediatric rheumatologic diseases. Because of its similarity in presentation to other conditions with overlapping manifestations, such as flares of rheumatologic disease or systemic infection, and the fact that there exists no single pathognomonic clinical finding or laboratory parameter to aid in diagnosis, MAS presents a significant diagnostic challenge to the practicing pediatrician with limited access to consulting pediatric rheumatologists. Along with a review of the physiology and manifestations of the condition, we have included the most current consensus for diagnosing MAS. [Pediatr Ann. 2019;48(10):e395-e399.].