Figure 19. Surgically proved testicular immature teratoma manifesting as a cystic mass in a 23-year-old man. Transverse US scan of right testis reveals multiple cystic areas (arrow) measuring 2-15 mm. Cystic areas involved nearly the entire testis, leaving only a rim of normal testicular parenchyma (arrowhead). These cystic changes can be easily differentiated from tubular ectasia, which is confined to the mediastinum and occurs in older men. (Reprinted, with permission, from reference 115.)