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Start free with EleplanMacrophage activation syndrome
ORPHA:158061Clinical syndrome
What it is
A rare hemophagocytic syndrome characterized by excessive activation and proliferation of macrophages and T cells occurring in the context of a variety of diseases, including infections, neoplasms, rheumatic disorders, and leading to sudden onset of persistent fever, lymphadenopathy, and hepatosplenomegaly. Complications include profound depression of one or more blood cell lines with coagulopathy and pancytopenia, and impaired liver and renal function. Bone marrow examination reveals numerous well differentiated macrophages actively phagocytosing hematopoietic elements.
Key facts
- Age of onset
- Adolescent, Adult, Childhood
- Classified as
- Clinical syndrome
Signs and symptoms
Very common80–99%
17- Abnormal circulating interleukin concentration
- Abnormality of tumor necrosis factor secretion
- Abnormal natural killer cell countDiagnostic criterion
- Anemia
- Autoimmunity
- Decreased liver function
- Elevated circulating alanine aminotransferase concentration
- Elevated erythrocyte sedimentation rate
- FeverDiagnostic criterion
- HemophagocytosisDiagnostic criterion
- Hypoalbuminemia
- Increased circulating ferritin concentrationDiagnostic criterion
- Increased circulating interleukin 6 concentration
- Increased circulating lactate dehydrogenase concentration
- Increased inflammatory response
- Increased serum interferon-gamma level
- Thrombocytopenia
Common30–79%
8- Decreased total neutrophil count
- Elevated circulating aspartate aminotransferase concentration
- Elevated circulating C-reactive protein concentration
- HypertriglyceridemiaDiagnostic criterion
- HypofibrinogenemiaDiagnostic criterion
- Juvenile rheumatoid arthritis
- Lymphadenopathy
- SplenomegalyDiagnostic criterion
These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.
ICD-10 codes
ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.
Cross-references
Orphadata Science: Free access data from Orphanet. © INSERM 1999. Data version 2026-06-23. Available under CC BY 4.0. This is a reference, not medical advice.
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