Pathology of variant Creutzfeldt-Jakob disease.

Variant Creutzfeldt-Jakob disease (vCJD) is a novel prion disease in man which was first described in 1996 in the UK. There is substantial evidence to indicate that vCJD represents the effects of the bovine spongiform encephalopathy (BSE) agent in man. The neuropathology of vCJD is characterised by the florid plaque, composed of a central amyloid core with a fibrillary periphery, surrounded by a rim of spongiform change in an intact neuropil. Unique patterns of PrP accumulation in vCJD are revealed by immunocytochemistry in the cerebral and cerebellar cortices, the basal ganglia, thalamus and brainstem. The neuropathology of the thalamus and midbrain is also characterised by severe neuronal loss and gliosis. vCJD is distinct from other human prion diseases in that disease-associated PrP accumulates within follicular dendritic cells in lymphoid tissue, and consistently in peripheral sensory ganglia. All vCJD patients so far have been methionine homozygotes at codon 129 in the PrP gene. There is no evidence to indicate that cases of BSE infection have occurred in individuals in the UK who are MV or VV at codon 129 in the PrP gene. It is conceivable that BSE incubation periods in these groups may be longer than in methionine homozygotes, hence the precise numbers of future cases of vCJD are difficult to estimate at present.