Introduction B cell lymphoma with monoclonal IgM production type of non-Hodgkin lymphoma Presentation Presents in older individuals Symptoms constitutional symptoms fatigue and headache generalized lymphadenopathy petechial bleeding IgM disrupts platelet aggregation anemia Raynaud phenomenon sequelae of blood hyperviscosity and cold agglutinins retinal hemorrhage stroke decreased renal function Evaluation Labs ↑ ESR, LDH, alkaline phosphatase, and uric acid Bone marrow biopsy abnormal plasma cells contains intranuclear aggregations of IgM (Dutcher bodies) Serum protein electrophoresis M spike = IgM unlike multiple myeloma which is IgA/G Urine Bence Jones proteins will be present Ig light chains urine dipstick will be negative for protein as it detects only albumin Imaging no lytic bone lesions Treatment Symptomatic only rituximab Plasmapheresis when hyperviscosity is present