CD40LG and lymphoma: A MAG antibody titer of 1:102400 was detected. He was noted to have a monoclonal spike of 0.8 g/dL, IgM of 390 mg/dL, kappa 2 of 7 mg/L, and a free kappa/lambda ratio of 2.1. A bone marrow biopsy on April 23, 2019, showed IgM-kappa-restricted surface light chain negative low-grade lymphoma, very dim cytoplasmic kappa restricted, CD138 < 5%, CD79a, CD19, CD20 (predominantly strong), CD5 (variable, weak), CD23 (weak), IgM (weak), and kappa was negative for CD3, cyclin D1, lambda, IgG, IgD, IgA, and MYD88 negative.