A 7-year-old girl develops high spiking fever (>39°C) for 3 weeks, evanescent salmon-pink rash coinciding with fever spikes, and arthritis of the knees and wrists. Ferritin is 12,000 ng/mL. RF and ANA are negative. The diagnosis is systemic JIA (sJIA). The drug with a unique mechanism targeting IL-18 and IFN-γ to prevent macrophage activation syndrome (MAS) is:
- A Methotrexate
- B Anakinra (IL-1 receptor antagonist)
- C Emapalumab (anti-IFN-γ monoclonal antibody) ✓
- D Tocilizumab (anti-IL-6 receptor)
Correct answer: C. Emapalumab (anti-IFN-γ monoclonal antibody)
Explanation
Macrophage activation syndrome (MAS) is a life-threatening complication of sJIA driven by uncontrolled cytokine storm involving IFN-γ and IL-18. Emapalumab is an anti-IFN-γ monoclonal antibody specifically approved for primary and secondary HLH/MAS, targeting the central cytokine in the IFN-γ-driven hyperactivation. Anakinra (anti-IL-1) is used for sJIA arthritis and fever control but targets a different pathway. Tocilizumab (anti-IL-6R) is used for sJIA systemic features but does not specifically address IFN-γ-mediated MAS.
Reference: Ghai Essential Pediatrics, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.