Macrophage activation syndrome (MAS)

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Macrophage activation syndrome (MAS) occurs when the immune system is overactivated and causes inflammation. Learn about the signs, causes and treatment of MAS.

Key points

  • MAS is severe inflammation of the entire body and is a very serious condition.
  • MAS is usually associated with rheumatologic conditions, infections and cancers.
  • MAS, when diagnosed, must be monitored closely and treated promptly.
  • If treated appropriately, most children respond well to therapy.
Last updated: April 29th 2024