hematology and oncology
Macroglobulinemia
Introduction
Macroglobulinemia is a malignant plasma cell disorder in which B cells produce excessive amounts of IgM M-proteins. Manifestations may include hyperviscosity, bleeding, recurrent infections, generalized adenopathy, and hepatosplenomegaly. Diagnosis requires bone marrow examination and demonstration of M-protein. Treatment includes plasma exchange as needed for hyperviscosity and systemic therapy with alkylating drugs, corticosteroids, nucleoside analogs, Bruton's tyrosine kinase (BTK) inhibitors,venetoclax, or monoclonal antibodies. (See also Overview of Plasma Cell Disorders .) Macroglobulinemia, an uncommon B-cell cancer, is clinically more similar to a lymphomatous disease than to Multiple Myeloma and other After myeloma, macroglobulinemia is the 2nd most common malignant disorder associated with a monoclonal gammopathy. Excessive amounts of IgM M-proteins (monoclonal immunoglobulin protein, which may consist of both heavy and light chains or of only one type of chain) can also accumulate in other disorders, causing manifestations similar to macroglobulinemia. Small monoclonal IgM components are present in the sera of about 5% of patients with B-cell Non-Hodgkin Lymphomas ; this circumstance is termed macroglobulinemic lymphoma. Additionally, IgM M-proteins are occasionally present in patients with Clinical manifestations of macroglobulinemia include bleeding, recurrent infections, generalized adenopathy, and hepatosplenomegaly. Less commonly, patients develop hyperviscosity due to the large amounts of high molecular weight monoclonal IgM proteins circulating in plasma, but most patients do not develop problems related to high IgM levels. Some of these proteins are antibodies directed toward autologous IgG (rheumatoid factors) or I antigens (cold agglutinins). About 10% are cryoglobulins. Amyloidosis occurs in 5% of patients. 