- Corticobasal degeneration (CBD) has substantial overlap of clinical features with other neurodegenerative diseases including Parkinson's disease (PD). Its clinical diagnostic accuracy is the lowest among the common neurodegenerative diseases, and its antemortem diagnosis is more challenging when CBD is comorbid with another brain disease. We report an elderly male patient with multiple medical conditions and a family history of essential tremor. He presented with progressive tremor that was initially thought to be essential tremor and later diagnosed as PD despite head computerized tomography showing bilateral intraventricular masses and other minor changes. The clinical diagnosis of PD was supported by his responsiveness to low-dose levodopa. However, postmortem neuropathological examination revealed CBD and bilateral choroid plexus xanthogranulomas with mild ventricular enlargement and multifocal ependymal lining injury presumably due to mild hydrocephalus. CBD is typically levodopa-unresponsive, but hydrocephalus-associated parkinsonism is commonly levodopa-responsive. We raise awareness of the present comorbidity and atypical parkinsonism due to the choroid plexus xanthogranuloma-induced hydrocephalus for the clinical diagnosis and management of parkinsonism.