[JC virus infection and lympho-plasmocytic infiltration of the central nervous system revealed by a cerebellar syndrome].

We report the case of a 74 year-old woman who had been treated since 8 years for a Waldenström's disease. She also was affected by a progressive multi-focal leukoencephalopathy. The interest of this case lies in two principal features. On the one hand, the clinical and radiological signs were restricted to the cerebellum and to the brainstem, on the other hand, brain examination revealed lymphocytes and plasma cells infiltration suggestive of an associated Bing and Neel syndrome.