Testicular cancer grows inside the testicle itself, not on the scrotum (the sack of skin that holds the testicles). Nearly all testicular cancers begin in the germ cells, which are the sperm-producing cells deep within the testicle. If you feel a lump on the outer skin of the scrotum, that’s a different issue entirely.
Where Exactly the Cancer Starts
The testicles sit inside the scrotum, which is simply a loose pouch of skin. Testicular cancer originates in the tissue of the testicle itself, not in the surrounding skin or pouch. The most common sign is a painless, hard lump that you can feel on or within the testicle when you roll it between your fingers. The lump is embedded in the firm, oval-shaped gland, not floating freely in the sack around it.
This distinction matters because the scrotum and the testicle are made of completely different types of tissue. The scrotum is skin and muscle. The testicle is a gland packed with cells that produce sperm and hormones. Cancer of the scrotal skin is extremely rare and would be classified as skin cancer, not testicular cancer. When doctors say “testicular cancer,” they mean a tumor growing inside the gland.
What a Testicular Lump Feels Like
A cancerous lump typically feels like a hard, painless mass attached to or within the testicle. It doesn’t move independently the way a cyst on the skin might. You may also notice that one testicle feels heavier than the other, or that the overall shape or firmness of the testicle has changed. Pain is not a reliable warning sign. Most testicular cancers don’t hurt, especially early on.
Lumps on the Sack Are Usually Something Else
Several common, non-cancerous conditions cause lumps or swelling in the scrotal area that can be confused with testicular cancer. The key difference is where the lump is located relative to the testicle itself.
- Hydrocele: A buildup of fluid in the thin sheath surrounding the testicle. This creates swelling in the scrotum that may feel like the whole sack is enlarged, but the testicle inside is normal.
- Varicocele: Enlarged veins around the testicle, often described as feeling like a “bag of worms” above or behind the testicle. More noticeable when standing.
- Spermatocele: A painless, fluid-filled cyst near the top of the testicle, in the area of the epididymis. These are benign.
- Inguinal hernia: A portion of intestinal tissue pushing through a weak spot in the abdominal wall and into the scrotal area. This creates bulging that can look like a scrotal mass but has nothing to do with the testicle.
- Epididymitis: Inflammation of the coiled tube at the back of the testicle. Unlike cancer, this is usually painful and tender, and the discomfort tends to come on gradually.
None of these are testicular cancer, though some of them still benefit from medical evaluation. The important takeaway: a lump you feel on the skin of the scrotum, or swelling around (but not within) the testicle, is far more likely to be one of these benign conditions.
How to Tell the Difference Yourself
A self-exam is the simplest way to learn what’s normal for your body and catch changes early. The Cleveland Clinic recommends doing it while standing, ideally after a warm shower when the scrotal skin is relaxed. Lift your penis out of the way and visually inspect the scrotum first. Then gently grip the top of the scrotum and locate one testicle.
Roll the testicle slowly between your thumb and fingers, feeling for any hard lumps or changes in texture. The testicle should feel smooth and firm, like a hard-boiled egg. At the top and back of each testicle, you’ll feel a softer, slightly squishy tube called the epididymis. This is normal and can feel tender to the touch. Above that, you’ll find the spermatic cord, which feels like a small rope. These structures are not lumps. Repeat on the other side.
What you’re looking for is anything new, hard, or fixed within the body of the testicle itself. A pea-sized hard spot that wasn’t there before is worth getting checked, even if it doesn’t hurt.
Who Gets Testicular Cancer
Testicular cancer is uncommon overall. About 0.4 percent of men will be diagnosed with it at some point in their lives, with roughly 9,810 new cases expected in the United States in 2026. It most often affects younger men, typically between ages 15 and 35.
The strongest known risk factor is a history of an undescended testicle (cryptorchidism). Men with this condition have roughly 3.7 times the risk of developing testicular cancer compared to men whose testicles descended normally. This elevated risk applies even if the condition was surgically corrected in childhood.
The good news is that testicular cancer is one of the most treatable cancers. The five-year survival rate is 94.6 percent across all stages. When caught early, before the cancer has spread beyond the testicle, the outlook is even better.