Neurosyphilis Initially Misdiagnosed as Behavioral Variant Frontotemporal Dementia: Life-Changing Differential Diagnosis.

Diagnosing neurosyphilis can be challenging and it may be misdiagnosed as behavior variant frontotemporal dementia, given its affinity for the frontal and temporal lobes. Here we present a model case, who, in his 40 s, was initially misdiagnosed with behavioral variant frontotemporal dementia based on extreme self-neglect and disinhibition over six months and frontal lobe atrophy. He was later diagnosed as neurosyphilis with positive syphilis tests in his cerebrospinal fluid. He underwent penicillin treatment and fully recovered. Relatively rapid cognitive decline, particularly if young, should prompt physicians to consider neurosyphilis as a treatable dementia, which could completely change a patient's life.