Delayed postischemic leukoencephalopathy after large vessel occlusion: Imaging and histopathologic correlation

Delayed postischemic leukoencephalopathy (DPIL) is an under-recognized cause of delayed white matter injury following cerebral ischemia. We report the case of a 71-year-old woman who presented with delayed neurological deterioration 3-4 weeks after successful mechanical thrombectomy for left middle cerebral artery occlusion. Serial brain MRI documented progressive T2/FLAIR hyperintensity with moderate diffusion restriction confined to the vascular territory's subcortical white matter, strictly sparing the cortex and subcortical U-fibers. Extensive diagnostic work-up excluded infectious, autoimmune, and toxic causes. To exclude a suspected primary central nervous system lymphoma, a stereotactic brain biopsy was performed, demonstrating myelin loss, relative axonal preservation, and reactive gliosis without malignancy. To our knowledge, this case provides rare histopathological correlation supporting DPIL after large-vessel occlusion. Recognizing this specific territorial radiologic-pathologic pattern is essential to avoid misdiagnosis and unnecessary invasive diagnostic interventions in patients with secondary neurological worsening.