<prompt> What is the histological appearance of brain in Creutzefeldt Jakob diseaseNeuronophagiaSpongiform change in brainMicroabscessDemylination  <response>: Refer Robbins page no 1282MORPHOLOGY The progression of the dementia in CJD is usually so rapid that there is little if any grossly evident brain atrophy. The pathog- nomonic finding is a spongiform transformation of the cerebral coex and, often, deep gray matter structures caudate, putamen; this multifocal process results in the uneven forma- tion of small, apparently empty, microscopic vacuoles of varying sizes within the neuropil and sometimes in the perikaryon of neurons Fig. 28-32A. In advanced cases there is severe neu- ronal loss, reactive gliosis, and sometimes expansion of the vacuolated areas into cystlike spaces status spongiosus. Inflammation is notably absent. Electron microscopy shows the vacuoles to be membrane-bound and located within the cyto- plasm of neuronal processes. Kuru plaques are extracellular deposits of aggregated abnormal protein; they are Congo red- and PAS-positive and usually occur in the cerebellum Fig. 28-32B, but are abundant in the cerebral coex in cases of vCJD Fig. 28-32C. In all forms of prion disease, immuno- histochemical staining demonstrates the presence of protein- ase K-resistant PrPsc in tissue. 