A 75-year-old woman with Waldenstrom macroglobulinemia: T1-weighted (600/20, TR/TE) axial (A) and sagittal T1-weighted (600/20, TR/TE) precontrast (B) and postcontrast (C) MR images of the lumbosacral spine. Note diffuse pattern of marrow infiltration and enlarged retroperitoneal lymph nodes (arrows). The abnormal marrow is isointense to the intervertebral discs on the precontrast image and enhances markedly becoming hyperintense to the discs on the postcontrast image.