What is the differential for this retroperitoneal mass?
Most likely represent nodal enlargement. Possibilities in thus young patient include lymphoma and testicular neoplasms.
CT of the abdomen and pelvis demonstrates a large para-aortic mass which in places encases the aorta. It is well circumscribed and has a few small vessels passing through it. The mass results in left-sided ureteric obstruction and hydronephrosis.
An abnormality in the left hemiscrotum can be seen on the most caudal aspect of both axial and coronal reconstructions.