Scrotal masses are abnormalities in the scrotum, according to Mayo Clinic. The scrotum is the bag of skin hanging behind the penis that contains the testicles. Scrotal masses may be an accumulation of fluids, abnormal tissue growth or normal scrotal contents that have become swollen, inflamed or hardened.
Scrotal masses can be benign or malignant. Benign scrotal masses include varicocele, spermatocele, hydrocele and hematocele, according National Institutes of Health (NIH).
Varicocele is enlargement of the veins within the scrotum, according to Mayo Clinic and The American Academy of Family Physicians (AAFP) describes it as a "bag of worms."
NIH says spermatocele is a cyst-like scrotal mass containing fluid and dead sperm cells. Hydrocele is fluid collection in the scrotum. Hematocele is blood collection within the scrotum caused most likely by traumatic injury.
Another type of scrotal mass is testicular torsion. Mayo Clinic says this is a twisted spermatic cord, blood vessels, nerves and tube that carries semen from the testicle to the penis.
Other scrotal masses can be caused by inflammatory or infectious diseases, physical injury, herniation or tumors, according to NIH.
Mayo Clinic says orchitis is inflammation of the testicle usually due to a viral infection. Epididymitis is often caused by a bacterial infection, including sexually transmitted infections, such as chlamydia and gonorrhea.
AAFP says an inguinal hernia can show itself as a scrotal mass. Mayo Clinic defines an inguinal hernia as where a portion of the small intestine pushes through an opening or weak spot in the tissue separating the abdomen and groin.
Although rare, testicular cancer is the most concerning cause of a painless scrotal mass. Testicular cancer is a tumor containing abnormal testicular tissue, according to Merck Manuals. NIH lists painless or painful scrotal bulge or lump, infertility and an enlarged scrotum as symptoms of scrotal masses.
Mayo Clinic adds that pain radiates throughout the groin, abdomen or lower back.