Glial localization of four-repeat tau in atypical progressive supranuclear palsy.

In the present case, a patient in whom limb apraxia and asymmetrical parkinsonism developed suggesting corticobasal degeneration, is reported. Neuropathologic examination revealed numerous tufted astrocytes in the precentral cortex in addition to the characteristic pathologic findings of PSP. Therefore, on the basis of clinicopathologic features, atypical progressive supranuclear palsy was diagnosed. In addition, the brain tissue of the present patient was investigated with an antibody specific for four-repeat tau (4R-tau). In the precentral cortex, numerous tau-positive tufted astrocytes, pretangles, and threads were positive for 4R-tau. Using a confocal microscopy we demonstrated that tufted astrocytes positive for 4R-tau were adjacent to astrocytes positive for GFAP. The present findings suggest that accumulation of four-repeat tau in astrocytes is a degenerative process rather than a reactive process.