A 6-year-old girl has been having daily high-spiking fevers for 3 weeks with quotidian (once or twice daily) pattern, evanescent salmon-colored rash appearing with fever, hepatosplenomegaly, and a markedly elevated ferritin (12,000 ng/mL). RF and ANA are negative. The most likely diagnosis and a complication to screen for is:
- A Systemic JIA (Still's disease) — screen for macrophage activation syndrome (MAS) with serial ferritin, LFTs, and CBC ✓
- B Systemic lupus erythematosus — screen for renal involvement
- C Kawasaki disease — screen for coronary aneurysms
- D Acute rheumatic fever — carditis screening with echo
Correct answer: A. Systemic JIA (Still's disease) — screen for macrophage activation syndrome (MAS) with serial ferritin, LFTs, and CBC
Explanation
Systemic juvenile idiopathic arthritis (sJIA/Still's disease) presents with quotidian fever, evanescent salmon-pink rash (pathognomonic — appears with fever peaks), arthritis, hepatosplenomegaly, and markedly elevated ferritin. The life-threatening complication is Macrophage Activation Syndrome (MAS/secondary HLH) — characterized by persistently elevated and paradoxically rising ferritin, cytopenias (despite active inflammation), elevated transaminases, and coagulopathy. Serial monitoring of ferritin, LFTs, and CBC is mandatory in sJIA.
Reference: Ghai Essential Pediatrics, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.