CD40LG and lymphoplasmacytic lymphoma: However, plasma electrophoresis did not revealed free heavy-chain and smears and flow cytometry of the bone marrow aspirate were consistent with the lymphoplasmacytic lymphoma without detection of IgM positive light-chain negative lymphoplasmacytoid lymphocytes [20], Therefore, we speculate that the identified mu heavy-chain was derived from monoclonal IgM-kappa that non-specifically co-deposited with amyloid fibrils [5], while the exact origin remains unknown.