Close relationship between spongiform change and ubiquitin-positive granular structures in diffuse Lewy body disease

The origin of spongiform change seen in diffuse Lewy body disease (DLBD) cases was elucidated, as compared with Alzheimer-type dementia (ATD) cases. Spongiform change was composed of numerous vacuoles in the neuropil, predominantly in layers II-IIIab of the transentorhinal cortex and in the intermediate area of the accessory basal amygdaloid nucleus. The distribution of spongiform change was identical to that of ubiquitin-positive granular structures (UPG) in non-demented cases. The degree of spongiform change was correlated with loss of the large pyramidal neurons in layers IIIc and V of the transentorhinal cortex and with the disappearance of their ubiquitin-positive granular processes. With electron microscopy, the early vacuoles of spongiform change appeared to arise in the presynaptic terminals as well as in the postsynaptic terminals and dendritic processes. These findings indicate that the vacuoles derive from degeneration of terminal axons of the large pyramidal neurons. The occurrence of spongiform change characteristic to DLBD suggests that the large pyramidal neurons degenerate more rapidly in DLBD than in ATD.