Early-onset Alzheimer Disease Mimicking Frontotemporal Dementia: Hippocampal-sparing and Cerebellar Amyloid (autopsy)

Behavioral variant Alzheimer disease (bvAD) is an atypical form of AD that may closely mimic behavioral variant frontotemporal dementia (bvFTD). We describe an autopsy-confirmed case of early-onset AD presenting with a bvFTD-like behavioral syndrome. The case showed frontal and temporal lobe-predominant neurodegeneration, relative hippocampal preservation, sparse mature hippocampal NFTs with prominent pretangle-like tau inclusions, and atypical cerebellar amyloid deposits. Neuropathological diagnosis was Alzheimer disease with high-level AD neuropathologic change: A3/B3/C3. This case supports the importance of autopsy-based clinicopathological studies for clarifying the spectrum of bvAD.

Keywords: behavioral variant Alzheimer disease; bvAD; behavioral variant frontotemporal dementia; bvFTD; hippocampal-sparing Alzheimer disease; early-onset Alzheimer disease; neurofibrillary tangles; pretangle; cerebellar amyloid; autopsy; neuropathology.