This patient has a testicular mass. Let's examine a few differentials as we go through the answer choices.

Germinal Cell Tumor (Testicular Tumor)

• Usually painless but dull/achy/heavy sensation; palpation of SOLID mass
• No change in size when supine
• No transillumination

Dilated pampiniform venous plexus (Varicocele)

• Usually painless; "Bag of worms"
• Reduced swelling when supine
• No transillumination

Cystic Dilation of the effect ductules (Spermatocele)

• Typically painless; fluctuant swelling of upper testicular pole
• No change in size when supine
• Does transilluminate

Fluid accumulation within the tunica vaginalis testis (Hydrocele)

• Often painless; fluctuant swelling of scrotum
• May/May not change in size wrt position
• Does transilluminate

Vascular Trauma (Hematocele/Ruptured Testis)

• Extremely painful & tender; visible hematoma
• May/May not change in size wrt position
• No transillumination