Figure 11a. Round cell liposarcoma in a 34-year-old man. (a) Axial T2-weighted (6,000/112) MR image reveals a large mass (M) with heterogeneous but overall high signal intensity that originates from the posterior chest wall, fills the thoracic cavity, and displaces the aortic arch (A). (b) Photomicrograph (original magnification, x200; hematoxylin-eosin stain) shows atypical round cells in a myxoid background that accounts for the very high signal intensity on the T2-weighted MR image.