Neuropathological diagnostic criteria for Creutzfeldt-Jakob disease (CJD) and other human transmissible spongiform encephalopathies (prion diseases) are proposed for the following disease entities: CJD--sporadic, iatrogenic (recognised risk) or familial (same disease in 1st degree relative): spongiform encephalopathy in cerebral and/or cerebellar cortex and/or subcortical grey matter; or encephalopathy with prion protein (PrP) immunoreactivity (plaque and/or diffuse synaptic and/or patchy/perivacuolar types). Gerstmann-Sträussler-Scheinker disease (GSS) (in family with dominantly inherited progressive ataxia and/or dementia): encephalo(myelo)pathy with multicentric PrP plaques. Familial fatal insomnia (FFI) (in member of a family with PRNP178 mutation): thalamic degeneration, variable spongiform change in cerebrum. Kuru (in the Fore population). Without PrP data, the crucial feature is the spongiform change accompanied by neuronal loss and gliosis. This spongiform change is characterised by diffuse or focally clustered small round or oval vacuoles in the neuropil of the deep cortical layers, cerebellar cortex or subcortical grey matter, which might become confluent. Spongiform change should not be confused with non-specific spongiosis. This includes status spongiosus ("spongiform state"), comprising irregular cavities in gliotic neuropil following extensive neuronal loss (including also lesions of "burnt-out" CJD), "spongy" changes in brain oedema and metabolic encephalopathies, and artefacts such as superficial cortical, perineuronal, or perivascular vacuolation; focal changes indistinguishable from spongiform change may occur in some cases of Alzheimer's and diffuse Lewy body diseases. Very rare cases might not be diagnosed by these criteria. Then confirmation must be sought by additional techniques such as PrP immunoblotting, preparations for electron microscopic examination of scrapie associated fibrils (SAF), molecular biologic studies, or experimental transmission.

Creutzfeldt-Jakob disease (CJD) and Alzheimer's disease (AD) share clinical, neuropathological, and pathogenetic features. To investigate eventual mutual influences, we screened prominently affected neocortex from 110 neuropathologically proven CJD patients for Alzheimer-type pathology with anti-beta/A4, Bielschowsky and anti-tau (immuno)stains. The neuropathological classification of Alzheimer-type pathology was made according to the CERAD criteria. Results were controlled by comparison with Alzheimer-type changes in sections from the same cortical areas in 110 sex- and age-matched non-demented control patients. For comparison, the control patients were also classified according to the CERAD neuropathology criteria as if they had been demented. Alzheimer-type tissue changes as in definite and probable CERAD AD occur in 10.9% of the CJD patients and 19.1% of control patients (P=0.11). The median age of CJD and control patients with CERAD AD is 72 and 68 years, respectively, which differs significantly from the median ages of 64 and 63 years, respectively, in the non-AD/CJD and non-AD control patients. Since CERAD criteria include "presence of other neuropathological lesions likely to cause dementia", an AD diagnosis in CJD patients (all of whom are demented) is solely based on densities of neuritic plaques. Similar Alzheimer-type changes in even higher frequency, however, are also present in elderly non-demented controls. Thus, the coexistence of Alzheimer-type pathology in CJD most likely represents an age-related change. Deposits of prion protein (PrP) frequently accumulate at the periphery of beta/A4 plaques. The presence of beta/A4 amyloid in the brain may influence PrP morphogenesis.

Samples of the hippocampus of four patients with Down's syndrome [two men aged 35 and 36 years with no evidence of Alzheimer's disease (AD) and two patients aged 47 and 55 years with associated AD] were obtained at post mortem and processed according to the rapid Golgi method. A significant reduction in the number of dendritic spines (DS) was found in the apical (middle, distal and oblique segments) and basilar (thick and thin segments) dendritic arbors of CA1 and CA2-3 pyramidal neurons in patients with Down's syndrome and no AD when compared to age-matched controls. An additional decrease of DS in every segment occurred in Down's patients with associated AD when compared to age-matched controls and Down's patients with no AD. In Down's syndrome (either associated or not to AD) thin basilar dendrites were the most severely involved; in AD patients CA1 pyramids were more severely affected than pyramidal neurons of the CA2-3 subfield.

The presence and distribution of apoptotic cell death in multiple system atrophy (MSA) and morphologically related diseases were investigated by means of a modified terminal deoxynucleotidyl transferase-mediated nick end labeling method, comparing their distribution with that of glial cytoplasmic inclusions, immunohistochemically demonstrated bcl-2 protein, bax protein, CD95, TNFalpha, and p53-protein expression, as well as activated microglia. Apoptosis occurred almost exclusively in oligodendrocytes in multiple system atrophy and its general distribution was comparable to the already known oligodendroglial pathology in this disorder. Additionally, in about a quarter of glial cytoplasmic inclusions, there was upregulation of bcl-2-protein and coexpression with ubiquitin, suggesting a final attempt of involved cells to counteract apoptotic cell death. Bax protein was also demonstrated in oligodendroglial cells. A significant neuronal apoptosis was not observed in MSA; these cells might be destroyed secondarily to oligodendroglial apoptosis by necrosis or other forms of programmed cell death. These results emphasize the central role of oligodendroglial pathology in multiple system atrophy, making this disease unique among neurodegenerative diseases.

We investigated the age-related location, gender distribution, and histology of 107 brain tumors in children under 4 years of age seen in our department between 1984 and 1997. The male-to-female ratio was 1.4 (62/45 cases) with a prevalence of supratentorial tumors (60/47 = 1.3); the main histological entity was astrocytoma (33.6%), followed by ependymoma (14.0%). In the 1st year of life 22 cerebral neoplasms became clinically apparent. A higher ratio for supratentorial tumors was revealed (17/5 = 3.4), but without gender preference, and primitive neuroectodermal tumors (PNET) were the most frequent (5/22). In the 2nd year 25 tumors were found. The male-to-female ratio was 1.5 (15/10) and the supratentorial-to-infratentorial ratio, 1.1 (13/12). The two most common entities were astrocytoma and ependymoma (6 cases each). In addition, a survey of previously published investigations into this subject was performed and a compilation of data on 1960, 545 and 1084 tumors in children below the age of 1, 2 and 4 years, respectively, was prepared, which makes it the most extensive review of brain tumors of infancy and early childhood yet undertaken.

We report 14 biopsy cases of granular cell tumours (GCT) of the central nervous system (CNS) outside the pituitary gland. In six cases the granular cells determined the morphology (actual GCT), the other eight consisted of different CNS tumours with a varying granular cell component. Pronounced immunoreactivity for ubiquitin and alpha-1-antichymotrypsin could be found in all investigated tumours, while GFAP, neuron specific enolase, von Willebrand factor, vimentin, S-100 protein, alpha-1-antitrypsin, actin, and the neurofilaments 68 kDa and 160 kDa showed mostly weak positivity in some cases. Four out of eight GCT showed no immunoreactivity for MIB1; the other four cases had a proliferation index between 0.5% and 15%. Six out of nine cases were positive for p53. We consider granular cells to originate from different cell types. Thus, although morphologically identical, GCT are actually biologically heterogeneous. GCT of the CNS may represent gliomas of mostly astrocytic origin with a metabolically induced transformation of some tumour cells into granular cells.

A case of dysembryoplastic neuroepithelial tumour of the cerebellum occurring in a 28-year-old woman is presented. The lesion extended from the cortex of the inferior vermis upwards into the white matter. Histologically, it exhibited areas of microcystic cerebellar astrocytoma and glial regions with hamartomatous blood vessels as well as areas with oligodendrocyte-like cells (OLC) with a delicate, fibrillary stroma lying in a mucinous, often microcystic matrix. The OLC showed prominent rosette formation and immunohistochemical features suggesting neuronal, i.e. granule cell, differentiation.

We present the first case of cerebral splenosis, occurring in a 20-year-old man 15 years after posttraumatic splenectomy. He became symptomatic through seizures and was operated on for suspected meningioma of the right occipital pole. Histologic evaluation of the lesion revealed splenic tissue with matching immunohistochemical results. Because no penetrating head injuries were reported at the time of trauma, a hematogenous spread of splenic tissue has to be assumed.