The ultrasound should be able to tell whether this is a more benign lesion - like a cyst, varicocele, hydrocele - or something more ominous like cancer.
A negative CT would make lymphoma less likely.
Infection remains a possibility - tests to evaluate the urine, as well as a prostate exam should be considered.
If there continues to be confusion about the diagnosis, you can consider a biopsy - which would give a more definitive diagnosis.
This option can be discussed with your personal physician.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin, M.D.
kevinmd_b