Background: Reports of false beliefs may be a unique feature of behavioral variant frontotemporal dementia (bvFTD) but the nature of these experiences is unclear.
Objective: To report a case of pathologically verified Pick disease in a patient presenting with prominent and recurrent fantasies.
Methods: We describe the clinical, neuroradiologic, and neuropathologic findings of a 53-year-old woman presenting with fantasies and meeting Clinical Consensus Criteria for bvFTD.
Results: Early in her course, she reported interactions with different actors, having torrid affairs with them, and other related fantasies. When confronted with her false beliefs, she admitted that these relationships were imaginary. Autopsy revealed Pick disease with τ-immunoreactive Pick bodies in the frontal and temporal cortices, and in the hippocampi.
Conclusions: Fantastic thinking, or vividly experienced imagination, may be a manifestation of bvFTD that is distinct from delusions and confabulations and could be the source of previously reported delusions and confabulations in bvFTD.