What is macrophage activation syndrome (MAS)?

By William Aird

Typically refers to HLH occurring in patients with autoimmune disease and other rheumatological disorders.

Per La Rosee et al:

[MAS] refers to a subset of patients with hemophagocytic lymphohistiocytosis (HLH) arising on a background of systemic autoinflammation/autoimmunity and should be restricted to patients with Still’s disease, lupus, vasculitis, and other related autoimmune systemic diseases, because its treatment may differ from that recommended for other forms of secondary HLH.