Irregular presence of abnormal prion protein in appendix in variant Creutzfeldt-Jakob disease

We have investigated the presence of disease related prion protein (PrP Sc ) in appendix samples obtained at necropsy from four neuropathologically confirmed cases of variant Creutzfeldt-Jakob disease (vCJD). PrP Sc was detected in only one vCJD appendix, at a level lower than found in a diagnostic tonsil biopsy sample obtained from the same patient. The single PrP Sc positive appendix, but not the other samples, also showed abnormal prion protein immunohistochemistry. The finding that appendix samples from three of four cases of vCJD are devoid of detectable PrP Sc questions the utility of screening archival appendicectomy tissues to estimate the prevalence of pre-clinical vCJD infection within the UK population.