Figure 15. Plexiform neurofibromatosis in an 18-month-old boy with chronic myeloid leukemia. He had multiple café au lait spots, and a posterior mediastinal mass was incidentally discovered on a chest radiograph. Coronal T1-weighted MR image (560/30) shows a well-defined paraspinal mass (arrowhead). Extensive plexiform neurofibromatosis affecting the right brachial plexus is also evident (arrows).