Ngo, Thu Hoa

85 year old man with progressive dementia and history of stroke clinically diagnosed with Alzheimer's disease (AD) came to autopsy. There was diffuse bilateral atrophy of the frontal/temporal lobes and focal cavitations grossly consistent with remote infarcts (confirmed microscopically) were noted in parietal lobe, basal ganglia, and cerebellar hemispheres. Microscopically, numerous tau inclusions including neurofibrillary tangles, globular inclusions, grains and threads with tau immunohistochemical stain were seen. Tau deposits were present throughout the brain with increased numbers in the limbic lobe, basal telencephalon and diencephalon. Leukoencephalopathy was due to atherosclerosis and deposition of amyloid β protein predominantly in the cortical capillaries, with diffuse cortical involvement. Only rare senile plaques were noted with amyloid immunostains. The distribution of tauopathy was unusual and similar to argyrophilic grain disease (AGD), however, the morphology of tau deposits seen are inconsistent with AGD. The presence of the cerebral amyloid angiopathy is unusual due to involvement of parenchymal capillaries outside the primary visual cortex and suggests a genetic component. A low Braak stage and scattered cortical plaques were insufficient for diagnosis of AD. To our knowledge the constellation of findings seen are unique and not previously reported.