[FTLD-U and Pick disease without Pick bodies--a clinical and pathological review]

Circumscribed cerebral lobar atrophy is observed in Pick disease with or without Pick bodies (conventional Pick disease) show circumscribed cerebral lobar atrophy. Pick disease with Pick bodies was initially termed as 3-repeat tauopathy to distinguish this disease from the conventional Pick disease. Case of Pick disease without Pick bodies formed a heterogeneous group. In all cases of Pick disease without Pick bodies, except for rare cases without any type of inclusions [dementia lacking distinctive histology (DLDH)] the presence of ubiquitinated inclusions was confirmed, which were broadly termed as frontotemporal lobar degeneration with ubiquitin-positive inclusions (FTLD-U). In Japan, the number of cases of Pick disease with Pick bodies and those with FTLD-U appears to be almost the same. The patterns of cerebral and subcortical nuclear degeneration are quite simillar in cases of Pick disease with Pick bodies and in cases of Pick disease with FLTD-U. Investigation of the motor neuron system in FTLD-U cases revealed that approximately two-third patients had mild to severe degeneration in the upper motor neural system (pyramidal tract). These cases of FTLD-U with motor neuron involvement formed an important group, namely, FTLD with motor neuron disease (FTLD-MND). Amyotrophic lateral sclerosis with dementia (ALS-D) in which degeneration of the lower motor neurons was generally prominent in comparison to the mild pyramidal tract degeneration in the case of FTLD-MND, is also a type of FTLD-MND. Thus, conventional Pick disease was further classified into Pick disease, FTLD-MND, FTLD-U (in a narrow sense), and DLDH.