Spectrum of diseases associated with IGM paraproteinemia

IgM monoclonal proteins constitute about 15% of all monoclonal gammopathies. Diseases associated with IgM monoclonal gammopathy range widely from silent laboratory abnormalities to diseases that can be aggressive and fatal, and this rare condition is often misdiagnosed because of its rarity and heterogeneity. Our aim in this study was to determine the underlying disease spectrum, presentations and prognoses of patients with IgM paraproteinemia. Our study included 48 patient with IgM paraproteinemia detected between July 26, 2007 and August 09, 2019 in Hacettepe University Hospitals with the presence of IgM type manoclonal protein detected by serum immunofixation methods and /or monitored between 2003 and 2019 by scanning from the Clinical Biochemistry Laboratory database. 17 of the patients were female (35.42%), 31 were male (65.58%), and the median age was 73 years (age range 40-92 years). In terms of final diagnoses, 23 patients (47.9%) had Waldenström's macroglobulinemia (WM), 12 patients (25%) indeterminate Non-Hodgkin lymphoma (NHL), 8 patients (16.67%) monoclonal gammopathy of unknown significance (MGUS), 2 patients (4.2%) had chronic lymphocytic leukemia (CLL), 1 patient (2.1%) had primary amyloidosis, and 1 patient (2.1%) had cryoglobulinemia. The median follow-up duration was 57.1 months. During the follow-up period, 33.33% (16 patients) of the patients died, 66.67% (32 patients) were alive. 78.3% of the patients diagnosed with Waldenström's macroglobulinemia, which was the most common diagnosis, were alive. Mortality rate was 50% in patients diagnosed with chronic lymphocytic leukemia or lymphoma. After 10 years of follow-up, 60% survival was observed in patients with WM. Consequently, monoclonal gammopathies have been recognized decades to centuries ago. When monoclonal gammopathies are discussed, most physicians think of multiple myeloma first, but MGUS and WM are other common causes of these disorders. On contrary to what is known, IgM paraproteinemia is more frequently related to diseases with malignant character such as WM and lymphoma than benign MGUS. And these patients, including those diagnosed with MGUS, should be under surveillance indefinitely.