# Neuroimaging-guided diagnosis of possible FTLD-FUS pathology: a case report

## TL;DR

A patient with memory loss and movement issues was diagnosed with FTLD-FUS using neuroimaging and clinical tests, despite no specific FUS biomarkers.

## Contribution

Demonstrates how neuroimaging and clinical features can guide diagnosis of FTLD-FUS in complex cases.

## Key findings

- Neuroimaging showed left-sided atrophy and hypometabolism consistent with FTLD-FUS.
- Exclusion of Alzheimer’s disease was confirmed via imaging and cerebrospinal fluid analysis.
- Combining clinical and imaging data improved differential diagnosis accuracy.

## Abstract

This case report presents a patient with progressive memory loss and choreiform movements.

Neuropsychological tests indicated multi-domain amnestic mild cognitive impairment (aMCI), and neurological examination revealed asymmetrical involuntary hyperkinetic movements. Imaging studies showed severe left-sided atrophy and hypometabolism in the left frontal and temporoparietal cortex. [18F]Flortaucipir PET exhibited moderately increased tracer uptake in hypometabolic areas. The diagnosis initially considered Alzheimer’s disease (AD), frontotemporal degeneration (FTD), and corticobasal degeneration (CBD), cerebral hemiatrophy syndrome, but imaging and cerebrospinal fluid analysis excluded AD and suggested fused-in-sarcoma-associated FTD (FTLD-FUS), a subtype of the behavioural variant of FTD.

Our case highlights that despite the lack of specific FUS biomarkers the combination of clinical features and neuroimaging biomarkers can guide choosing the most likely differential diagnosis in a complex neurological case. Imaging in particular allowed an accurate measure of the topography and severity of neurodegeneration and the exclusion of AD-related pathology.