Increased circulating IgM level Monoclonal immunoglobulin M proteinemia SNOMEDCT_US:35562000 Waldenstrom macroglobulinemia This is a characteristic feature of Waldenstrom macroglobulinemia (WM), which is defined as a B-cell lymphoplasmacytic lymphoma, characterized by monoclonal immunoglobulin M protein in the serum and infiltration of bone marrow with lymphoplasmacytic cells. SNOMEDCT_US:190818004 HP:0005508 Presence of a monoclonal immunoglobulin M protein in the serum. SNOMEDCT_US:190817009 UMLS:C0024419 Lymphoproliferative disorder Paraproteinemia