Section Editor: Sandy Cheng-Yu Chen, M.D.
Taipei Medical University Hospital, Taipei, Taiwan
Acute necrotizing encephalopathy (ANE) is a rare, parainfectious disorder with global distribution that typically affects young children and is usually preceded by a virus-associated illness. Pathogenesis is obscure, mainly due to an exaggerated immune response, which is referred to as a “cytokine storm.” Recurrent or familial ANE has been linked to a mutation in RAN binding protein 2 (RANBP2). The classic features are bilateral symmetric involvement of the thalami (A, arrows) with variable involvement of cerebral white matter, the cerebellum, putamina, brain stem, and rarely the spinal cord. Imaging features rapidly evolve (B and C, necrosis on day 5, arrows) into laminated patterns (C, arrows) due to central necroses, cytotoxic edema, and outer vasogenic edema plus petechial hemorrhage. The disease course is usually fulminant with poor prognosis.