Two pediatric cases of influenza-associated acute necrotizing encephalopathy with different clinical outcomes: a comparative case report

Acute necrotizing encephalopathy (ANE) is a rapidly progressive encephalopathy characterized by sudden neurological deterioration, multifocal symmetric brain lesions, and high mortality, and it is frequently associated with viral infections such as influenza.Cytokine-mediated disruption of the blood-brain barrier is considered a key pathogenic mechanism, and early indicators of disease severity may aid prognostication.We report two pediatric cases of influenza A-associated ANE with markedly different clinical outcomes.A previously healthy 34-month-old girl presented with abrupt altered mental status and seizures; laboratory evaluation demonstrated markedly elevated ferritin and transaminase levels accompanied by coagulopathy, and magnetic resonance imaging (MRI) revealed extensive bilateral involvement of the thalami, basal ganglia, brainstem, and cerebellum with central hemorrhagic necrosis.Despite treatment with high-dose methylprednisolone, her condition rapidly progressed to multiorgan failure, and brain death was confirmed on hospital day 8.In contrast, a 6-year-old girl presented with impaired consciousness following influenza A infection and exhibited only mild laboratory abnormalities, along with bilateral thalamic and deep white-matter lesions on MRI.She demonstrated neurological improvement within 48-72 hours of steroid therapy and was discharged with minimal deficits after rehabilitation.These contrasting cases highlight the heterogeneous clinical spectrum of ANE and suggest that early MRI patterns, systemic inflammatory markers, coagulation status, and early treatment response may provide important prognostic clues.Early recognition and comprehensive evaluation of clinical, laboratory, and imaging features may facilitate appropriate clinical decision-making in pediatric ANE.