A hydrocele is a collection of fluid inside the area of the scrotum, surrounding the testicle. Hydroceles are common in newborn infants and normally resolve after a few months after birth. The main symptom is a painless, swollen testicle, on one or both sides, which feels like a water-filled balloon. Hydroceles are usually not dangerous, and they are usually only treated when they cause discomfort or embarrassment, or they get so large that they threaten the blood supply of the testicle.

A spermatocele is a cyst-like mass that forms within the epididymis. It is usually filled with fluid and dead sperm cells. A spermatocele can be left untreated unless it is growing too large or causing the individual discomfort.

The male reproductive system, viewed from a sagittal section.

A scrotal mass is a lump or bulge that can be felt in the scrotum.