MYOM2 and demyelinating polyneuropathy: In patients with IgG or IgA M-protein, the incidence of peripheral neuropathy is lower than in patients with the IgM M-protein.[2] POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes) syndrome is a rare plasma cell disorder, which is characterized by demyelinating peripheral neuropathy.