Current treatment in macrophage activation syndrome worldwide: a systematic literature review to inform the METAPHOR project

Macrophage activation syndrome (MAS) is an hyperinflammatory life-threatening condition, part of the wide spectrum of haemophagocytic lymphohistiocytosis (HLH). The term MAS refers to a secondary form of HLH that complicates the course of rheumatological conditions. MAS is characterized by a marked hyperferritinaemia, cytopenia, liver insufficiency with coagulopathy, neurological manifestations and a high risk of rapid progression to multiorgan failure. Despite great improvement in diagnosis and management [1–9], MAS still represents a major challenge in clinical practice.