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 year s for a Waldenstrom'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 restri cted to the cerebellum and to the braimstem, on the other hand, brain exami nation revealed lymphocytes and plasma cells infiltration suggestive of an associated Sing and Neel syndrome.