Infant with enlarged left scrotum and elevated AFP

US of testicular yolk sac tumor
Transverse color doppler US of the scrotum (above) shows the left testicle is hypervascular and much larger in size than the right testicle. Sagittal US of the left testicle (below) shows the testicular enlargement is due to a large round mass in the superior aspect of the testicle that is discrete from the normal testicle inferiorly.

The diagnosis was yolk sac tumor of the testicle.