Creutzfeldt-Jakob disease (CJD) is characterized by a loss of neurons accompanied by astrogliosis and spongiform changes in the neuropil. It has been recognized that reactive microglia occur in CJD but little is known about the regional distribution and extent of the microglial activation. We have, therefore, examined six brains from cases of sporadic CJD by immunohistochemical labelling of grey and white matter microglia from frontal, parietal, temporal, and occipital lobes, striatum, thalamus, cerebellum and brain stem with RCA-1, LCA, CD68, HLA-DR, and HAM56. Microglial activation occurred in the grey matter where astrogliosis and prion protein (PrP) deposits were prominent. Processes of activated microglia surrounded the outer rim of spongy vacuoles. A diffuse microglial response was seen in the white matter that was immunophenotypically different from grey matter. Double-labelling with microglial markers and anti-PrP showed that activated microglia did not contain PrP-immunoreactivity. Therefore a primary role of microglia in PrP processing seems unlikely. Activated microglia may contribute to neuronal damage in CJD due to their cytotoxic potential.

We retrospectively analysed 13 patients (pts.) treated at the University of Tübingen from 1985 to 1993 to evaluate the results of radiation therapy (XRT) given as an adjuvant to totally or subtotally resected meningiomas. The overall survival was 38% at five years with a probability of relapse of 50% at this time. Reclassification of the tumours according to the new WHO-classification of brain tumours [14] revealed 10 grade-II-tumours (atypical meningioma) and 3 grade-III-tumours (anaplastic meningioma). Radiotherapy failed in all 3 pts. with macroscopically incomplete resection (Simpson's grade IV), who died with relapse between 4 and 51 months after radiotherapy. 5 out of 10 pts. with grade-II-tumours relapsed. All 3 pts. with grade-III-tumours died with relapse between 6 and 21 months after XRT. Morbidity was seen in 2 pts. after irradiation with 60 GY (ICRU dose specification). Complete surgical exstirpation offers the best possibility of tumour control. Grade-III-tumours should be irradiated whatever the extent of the primary surgery was. Our results might indicate a possible indication for XRT in pts. with atypical grade-II-tumours especially when radical surgery must be in doubt. Prospective multicentre trials are warranted to prove the prognostic value of the new WHO-classification for atypical and anaplastic meningiomas and to define the ultimate role of radiotherapy in this setting.

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