Polyneuropathy and monoclonal gammopathy of undetermined significance (MGUS); update of a clinical experience

Polyneuropathies associated with monoclonal gammopathy of undetermined significance (MGUS) encompass a group of phenotypically and immunologically heterogeneous neuropathies. While the best characterized is that associated with anti-myelin glycoprotein (MAG) antibodies, there are phenotypical and immunological neuropathy variants that still lack a clear classification. We analyzed a significant number of patients, in order to better evaluate the distribution of neuropathy phenotypes and to look for some common characteristics. Clinical, neurophysiological, and laboratory data from 87 consecutive MGUS patients with peripheral neuropathy were analyzed and compared among patient groups with different MGUS classes and autoantibody reactivity. Anti-MAG neuropathy cases account for the most homogeneous group with regard to clinical and neurophysiological findings. Patients with anti-gangliosides or sulfatide (GS) antibodies, despite a marked phenotype heterogeneity, still share several common features, including a younger age at diagnosis, a more severe disease, and a prompt and sustained response to both immunoglobulin and rituximab therapies, mostly requiring chronic administration of immune treatment. Although heterogeneous, MGUS-associated, anti-GS antibody positive neuropathies have important similar features possibly resulting from a similar biological background. •Polyneuropathies in patients with MGUS encompass a heterogeneous group of nerve disorders that lack a clear classification.•Patients with anti-MAG neuropathy have the most homogeneous clinical and neurophysiological findings.•Anti-GS neuropathy patients have a younger age at onset, a more severe disease, and a good response to immunotherapy.