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Macrophage Activation Syndrome — RACP Paediatrics MCQ

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HardRheumatologyMacrophage Activation SyndromeRACP Paediatrics

A 2-year-old boy presents with systemic JIA. He is commenced on naproxen. After 2 weeks, his fevers persist and he develops worsening hepatosplenomegaly, cytopenias (Hb 85 g/L, WBC 2.5 × 10⁹/L, Platelets 60 × 10⁹/L), triglycerides 5.8 mmol/L, and ferritin 25,000 mcg/L. ESR has paradoxically fallen from 85 to 12 mm/hr. What complication has occurred?

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Correct answer: D — Macrophage activation syndrome

The combination of cytopenias, very high ferritin, elevated triglycerides, falling ESR (paradoxical in active inflammation due to fibrinogen consumption), and hepatosplenomegaly in a child with systemic JIA is diagnostic of macrophage activation syndrome (MAS). MAS is treated with high-dose IV methylprednisolone and cyclosporine. Anakinra or etoposide may be required in refractory cases.

Reference: RCH Melbourne – 2024 – Clinical Practice Guidelines: Macrophage Activation Syndrome