Adult-onset Still Disease Complicated by Macrophage Activation Syndrome
Macrophage activation syndrome (MAS) is a severe, life-threatening complication of adult-onset Still disease. Recognising its characteristic clinical and laboratory constellation is essential to prompt and appropriate escalation of management.
Clinical Scenario — When to suspect MAS
MAS should be considered in adult-onset Still disease when the following features are present:
- Persistent fever
- Splenomegaly
- Elevated or rising serum ferritin
- Inappropriately low cell counts
- Abnormal liver function tests
- Intravascular activation of coagulation
- Elevated or rising serum triglycerides
Treatment Approach
When MAS proves refractory, the protocol involves specific targeted therapies — including agents that act on JAK1/JAK2 signalling pathways — alongside additional interventions. The complete sequencing, criteria, and options are set out in the full structured protocol.
References
DOI: 10.1136/ard-2024-225851
MAS should be considered in patients with persistent fever, splenomegaly, elevated or rising serum ferritin, inappropriately low cell counts, abnormal LFTs, intravascular activation of coagulation, elevated or rising serum triglycerides.
Finally, in refractory MAS, low-dose etoposide may also be considered.
Additionally, the potential interest of JAK inhibitors should be mentioned, since a few case reports reported efficacy of JAK1/JAK2 inhibitors-that is, ruxolitinib or baricitinib-in such patients.
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