Neuropathological discrepancy between Japanese Pick’s disease without Pick bodies and frontal lobe degeneration type of frontotemporal dementia proposed by Lund and Manchester Group

The concept of frontotemporal dementia (FTD) proposed by the Lund and Manchester group is useful because it distinguishes dementia with frontal and anterior temporal involvement from Alzheimer‐type dementia. The classification and definition of FTD and related disorders, however, are controversial. One point of controversy is the neuropathology of the frontal lobe degeneration (FLD) type of FTD. The FLD type is described as having mild frontal and anterior temporal atrophy and no accompanying tau or ubiquitin pathology. We investigated cases of Japanese Pick’s disease without Pick bodies (PB), the majority of which are thought to correspond to FLD type, in order to clarify whether the nature of the degeneration in these cases could be distinguishable from that in Japanese Pick’s disease with PB, which corresponds approximately to the Pick type of the Lund and Manchester group. Except for the presence of tau‐pathology, no obvious differences were noted between Pick’s disease without PB (FLD type) and Pick’s disease with PB (Pick type) either on neuropathological examination of own cases or a questionnaire survey of Japanese neuropathologists. The reason for this discrepancy may be based on the role of heredity, namely, most Japanese cases of Pick’s disease are solitary, while the FTD cases of the Lund and Manchester group were reportedly accompanied by extensive familial history. There is a possibility that Japanese, British, and Swedish neuropathologists deal with heterogeneous groups of dementia characterized as FTD without tau or ubiquitin pathology.