A 72-year-old Caucasian (white) man with a history of diffuse large B-cell lymphoma (DLBCL), immunoglobin M (IgM) monoclonal gammopathy of undetermined significance (MGUS), and chronic back pain secondary to osteoarthritis presented with dyspnea and a left pleural effusion. Here, CD40LG is linked to diffuse large B-cell lymphoma.