[Association between motoneuron disease and Waldenström macroglobulinemia].

The authors describe the case of a patient who was referred to their Unit because of polyneuropathy and was subsequently found to be affected by Waldenström's macroglobulinemia. A monoclonal paraproteinemia is frequently described in the serum of subjects with motor neuron disease. The association between motor neuron disease (MND) and lymphoproliferative disease (LPD) could be the result of a coincidence, but LPD seems to be disproportionally frequent in patients with MND, compared to the population in general. The literature has studied the time relationship between lymphoproliferative disease and MND and has examined the different possible mechanisms, which might explain the association between MND and LPD. The presence of a slight increase in the level of IgM and kappa chains in a patient with polyneuropathy induced us to carry out an aspiration and trephine bone marrow biopsies, which revealed the presence of a lymphoplasmocytoid infiltration, compatible with Waldenström's macroglobulinemia. A needle biopsy should be carried out as part of a diagnostic routine procedure in a patient with MND, especially in the presence of a monoclonal paraproteinemia.