Diffuse deposition of immunohistochemically labeled prion protein in the granular layer of the cerebellum in a patient with Creutzfeldt-Jakob disease.

Amyloid plaques in Creutzfeldt-Jakob disease, kuru, and Gerstmann-Sträussler-Scheinker syndrome are known to contain an abnormal isoform of a cellular protein, the prion protein (PrP). The prion protein in its normal cellular isoform is a membrane-bound glycoprotein of unknown function. The mechanisms causing a modification of PrP and accumulation in amyloid plaques are unknown. Here we present a case of Creutzfeldt-Jakob disease with widespread deposition of immunohistochemically labeled PrP in the internal granular layer of the cerebellum. Immunohistochemically labeled PrP was deposited in delicate granules, which often were associated with cellular processes or the cytoplams of undefined cells, or diffusely deposited in the neuropil.