a

b

Histologically proved yolk sac tumor in a 1-year-old boy with a painless unilateral scrotal mass. (a) Longitudinal US scan of the left hemiscrotum shows a solid tumor (T) replacing the entire testis. The cystic areas (arrowheads) represent tumor necrosis. (b) Contrast-enhanced abdominal CT scan, obtained during the initial work-up, shows retroperitoneal lymphadenopathy (L) with necrotic areas.

http://radiographics.rsna.org/content/25/5/1197.figures-only