hematology and oncology
Macroglobulinemia
Diagnosis of Macroglobulinemia
Complete blood count (CBC) with platelets, red blood cell indices, and a peripheral blood smear Serum protein electrophoresis followed by serum and urine immunofixation, quantitative immunoglobulin levels, and serum free light chain levels Plasma viscosity assay Bone marrow examination, including tests for specific mutations such asMYD88andCXCR4 Sometimes a lymph node biopsy Macroglobulinemia is suspected in patients with symptoms of hyperviscosity or other typical symptoms, particularly if anemia is present. However, it is often diagnosed incidentally when protein electrophoresis reveals an M-protein that proves to be IgM by immunofixation. Laboratory evaluation includes tests used to evaluate plasma cell disorders (see Multiple Myeloma ) as well as measurement of cryoglobulins, rheumatoid factor, and cold agglutinins; coagulation studies; and a direct antiglobulin (Coombs) test. Moderate normocytic, normochromic anemia, marked rouleau formation, and a very high erythrocyte sedimentation rate (ESR) may occur. Leukopenia, relative lymphocytosis, and thrombocytopenia are occasionally found. Cryoglobulins, rheumatoid factor, or cold agglutinins may be present. If cold agglutinins are present, the direct Coombs test usually is positive. Various coagulation and platelet function abnormalities may occur. Results of routine blood studies may be spurious if cold agglutinins, cryoglobulinemia, or marked hyperviscosity is present. Normal immunoglobulins are decreased in half of the patients. Immunofixation electrophoresis of concentrated urine frequently shows a monoclonal light chain (more often kappa [κ]), but gross Bence Jones proteinuria is unusual. Bone marrow studies show a variable increase in plasma cells, lymphocytes, plasmacytoid lymphocytes, and mast cells. Periodic acid-Schiff–positive material may be present in lymphoid cells. Lymph node biopsy, done if bone marrow examination is normal, is frequently interpreted as diffuse well-differentiated or plasmacytic lymphocytic lymphoma. 4.0 milliPascal-second (normal, 1.4 to 1.8 milliPascal-second) ( Diagnosis reference ). Retinal 1Gertz MA: Waldenstrom macroglobulinemia: 2023 update on diagnosis, risk stratification, and management.Am J Hematol98:348-358, 2023. doi:10.1002/ajh.26796 