IgM amyloidosis: clinical features in therapeutic outcomes.

It is not widely recognized that patients with amyloidosis may be associated with an IgM monoclonal protein. We reviewed the characteristics of 22 IgM amyloidosis patients seen at Mayo Clinic from 1989 through 2010 and uniformly treated with stem cell transplantation. IgM patients are older, have a higher prevalence of neuropathy, a lower incidence of cardiac involvement (lower troponin T and NT-proBNP), and a much lower level of the involved immunoglobulin free light chain.