Concentric structure of thalamic lesions in acute necrotizing encephalopathy.

Acute necrotizing encephalopathy of childhood (ANE) is characterized by multiple, symmetrical brain lesions affecting the bilateral thalami, putamina and cerebral white matter, which often show a concentric structure on CT and MRI. To reveal the pathological substrate of this finding, comparison was made between CT and necropsy findings of three fatal cases of ANE. Cranial CT demonstrated a concentric structure of the thalamocerebral lesions in one patient who died 3.5 days after the onset of encephalopathy, but not in the other two patients who died within 30 h. Neuropathological examination of postmortem brains revealed laminar changes of vascular and parenchymal pathology in all the cases. Excessive permeability of blood vessels and resultant vasogenic edema became more prominent with increasing depth from the cerebral surface. The deep portion of the lesions showed severe perivascular hemorrhage, accounting for the central high density on the CT images of one patient.