Hysteria or Dementia? A Case of Atypical Clinical Onset of Frontotemporal Dementia Associated with a Progranulin Mutation

The behavioral variant of frontotemporal dementia (bvFTD) is one of the main causes of neurodegenerative dementias in adults. Patients present with an early decline in social conduct, impaired regulation of interpersonal conduct, apathy, emotional blunting, and general loss of insight. However, symptoms are highly variable among patients, leading to misdiagnosis or diagnosis delay in particular when psychiatric symptoms are prominent at the onset of the disease. More specifically, personality disorders have been described as either a risk factor for misdiagnosis or as part of the bvFTD phenotype. Here we report the case of a 52-year-old woman, born from consanguineous parents and with a family history of early-onset dementia, who was first diagnosed with histrionic personality disorder according to the DSM-IV-TR criteria. Nonetheless, atypical symptoms such as apathy, disinhibition, hyperorality, depressive symptoms and psychotic manifestations were described.The clinical exam revealed a frontal lobe dysfunction, along with severe cognitive impairment as revealed by the neuropsychological assessment (alteration of facial emotion recognition and theory of mind, with a relative sparing of executive and instrumental functions). Brain imaging revealed atrophy of frontal lobes and right hemisphere, and a hypometabolism of the right frontotemporal lobe. Taking into consideration the clinical presentation and her family history, screening for hereditary diseases was performed, revealing a heterozygous mutation of PGRN gene. The diagnosis of bvFTD with progranulin mutation was finally made. This case highlights for the first time a diagnosis of bvFTD associated with a progranulin mutation and a history of late-labeled histrionic personality disorder. It emphasizes the need to actively seek frontal symptoms and consider PGRN mutation in late-labelled patients with personality disorders with a family history of neurodegenerative disorders.