An Autopsy Case of Progressive Dementia Showing Special Intraplasmic Inclusions in Diffuse Cerebral Cortex

: A 29-year-old male characterized by progressive dementia has been described. Histopathologically, the changes obtained were as follows: 1) Some atrophic nerve cells contained homogeneous round or oval intraplasmic inclusions which could be stained with periodic acid-Schiff and coupled tetrazonium. From these examinations the inclusions consisted of neutral mucopolysaccharide including protein. 2) Mild neuronal loss was diffusely present. 3) Most of the remaining nerve cells were atrophic. The above-described findings were observed diffusely in the whole cortex of the brain. To our knowledge, the present case does not belong to the category of any well-known pathological diseases.