Ultrastructural pathology of Gerstmann-Sträussler-Scheinker disease.

We report a detailed ultrastructural study based on a large series of samples from a recent case of Gerstmann-Sträussler-Scheinker disease from the original Austrian family. Numerous PrP-immunopositive plaques dominated light microscopic neuropathology. Ultrastructurally, several types of plaques were observed: unicentric "kuru," multicentric, and neuritic. Dystrophic neurites accompanied amyloid plaques to differing degrees. Plaques were enveloped by astrocytic processes and invaded by microglial cells. A prominent astrocytic reaction accompanied abundant spongiform change. Unusual crystalloids were observed in mitochondria while another type of crystalloid was seen within lysosomes. We conclude that Gerstmann-Sträussler-Scheinker disease is distinct also at the ultrastructural level.