[Involvement of central nervous system disclosing Waldenstrom's disease: demonstration of intrathecal secretion of immunoglobulin M].

We report the case of a 68-year old woman complaining of disorders of memory and persistent headaches in whom the diagnosis of Waldenström's macroglobulinaemia (WM) was made. Computerized tomography of the brain showed a butterfly-shaped hyperdensity in the splenium of the corpus callosum, with ventricular dilatation. Magnetic resonance imaging displayed high-intensity signals on T2-weighted sequences. Protein immunoelectrophoresis elicited an IgM kappa peak. The CSF was found to contain proteins and lymphocytes in excess, and immunohistochemical staining confirmed the predominance of anti-kappa and the presence of intrathecal IgM secretion. Chemotherapy was temporarily effective on the memory disorders, but the patient died 26 months after the beginning of treatment. Central nervous system manifestations are seldom observed in WM, and they are now grouped under the name of Bing-Neel syndrome. Psychic disorders are rarely reported. It is suggested that IgM secretion plays a predominant role in the pathogenesis of leucoencephalitis, and this is supported by the finding of intrathecal IgM synthesis.