Clinicopathological study of two subtypes of Pick's disease in Japan.

We examined the clinical and neuropathological findings in 3 cases of Pick's disease with Pick bodies (PiD) and 7 cases of atypical Pick's disease without Pick bodies (aPiD). PiD and aPiD cases corresponded clinically to frontotemporal dementia and semantic dementia, respectively, based on the clinical diagnostic criteria of frontotemporal lobar degeneration. Brain CT showed that cerebral atrophy was accentuated at an early stage of the illness in the anterior portion of the frontal lobes in PiD cases and in the anterior portion of the temporal lobes in aPiD cases. Neuropathologically, PiD cases showed more circumscribed lobar atrophy than aPiD cases. Both PiD and aPiD cases revealed moderate to severe degeneration with neuronal loss and gliosis in the affected cerebral cortex and subcortical nuclei, but only aPiD cases had pyramidal tract degeneration. Immunohistochemical analyses demonstrated that tauopathy with phosphorylated tau accumulation in the Pick bodies in PiD cases, while aPiD cases showed ubiquitinopathy with ubiquitin accumulation in the intraneuronal and dendritic inclusions. These findings suggested that two subtypes of Pick's disease in Japan can be distinguished not only neuropathologically but also clinically based on differences in pathogenesis.