Figure 7a. Seminoma of the mediastinum in a 37-year-old man with edema and swelling of the face and neck but no other symptoms. Chest radiography indicated a tumor of the upper mediastinum. (a) Axial T2-weighted MR image shows a large lobulated mass with several fibrovascular septa (arrows). (b) Axial contrast-enhanced T1-weighted MR image shows marked enhancement of the septa (arrows). (c) Photomicrograph (original magnification, x400; H-E stain) shows that the tumor is composed of large, rounded, clear cells.