Macrophage Activation Syndrome

**Semantic type:** Disease or Syndrome

**Definition:** A complication of rheumatic disease that is caused by excessive activation and uncontrolled proliferation of T lymphocytes and well-differentiated macrophages. It is characterized by fever, pancytopenia, liver insufficiency, coagulopathy and neurologic symptoms.

**Synonyms:** - MAS - MAS - Reactive Hemophagocytic Lymphohistiocytosis