Achromatic neurons in the cortex of progressive supranuclear palsy.

Achromatic neurons (AN) in the cerebral cortex are a characteristic feature of several neurodegenerative conditions including Pick's disease, corticobasal degeneration and some cases of primary progressive aphasia. Although AN are occasionally seen in some other diseases, their presence in progressive supranuclear palsy (PSP) has not been previously documented. We found significant numbers of AN in the cerebral cortex of five out of seven cases which had been diagnosed pathologically as PSP. The identification of AN was greatly facilitated by the use of neurofilament immunohistochemistry. The entorhinal and transentorhinal cortices were most frequently involved, but in several cases AN were also seen throughout the neocortex. The presence and number of AN roughly correlated with a history of clinical dementia. This suggests that cortical AN may be a common and important pathological finding in PSP.