[Behavioural variant of frontotemporal dementia as the presenting symptom of corticobasal degeneration]

The behavioural variant of frontotemporal dementia is characterised by progressive social, cognitive and personality deterioration associated with several molecular pathologies of frontotemporal lobar dementia (FTLD): FTLD-tau, FTLD-TDP and FTLD-FUS. Its diagnosis requires pathological studies.

A 61-year-old male, with a three-year progressive history of behavioural disorder, apathy, poor language skills, perseveration, lack of empathy, bulimia and executive dysfunction. Neuroimaging revealed right-dominant frontal cortical atrophy, and a single-photon emission tomography brain scan showed bilateral frontal hypoperfusion with thalamic and caudate involvement. Clinically, he was diagnosed with probable frontotemporal dementia, behavioural variant. On his death, his brain was donated to the Neurological Tissue Bank and the neuropathological diagnosis was corticobasal degeneration.

Corticobasal degeneration is one of the FTLD-tau tauopathies. The 2013 diagnostic criteria for corticobasal degeneration include executive dysfunction and behavioural and personality disorders similar to those of this patient as a clinical phenotype. The anatomoclinical case presented illustrates the absence of any correlation between the clinical phenotype and the underlying neuropathological diagnosis in frontotemporal dementia, and the need to conduct a histopathological study in order to reach a definitive diagnosis.