Most testicular lumps are not cancer. The majority turn out to be fluid-filled cysts, swollen veins, or excess fluid buildup, all of which are benign. That said, a lump on or in a testicle always deserves a medical evaluation because testicular cancer also starts as a lump, and catching it early makes a significant difference in outcomes.
The Most Common Causes
Several conditions can create a noticeable lump or swelling in the scrotum, and they feel quite different from one another.
A spermatocele (also called an epididymal cyst) is a fluid-filled sac that grows near the top of the testicle. It’s painless, benign, and often discovered by accident during a shower or physical exam. These cysts don’t need treatment unless they become large enough to cause discomfort.
A hydrocele is extra fluid that collects in the thin sac surrounding each testicle. There’s normally a small amount of fluid in that space, but when it builds up, you’ll notice painless swelling that can make one side of the scrotum look noticeably larger. Hydroceles are harmless on their own, though they sometimes signal an underlying issue worth investigating.
A varicocele is an enlargement of the veins inside the scrotum, similar to varicose veins in the legs. It’s far more common on the left side because of how blood drains differently from each testicle. A large varicocele can look and feel like a “bag of worms” sitting above the testicle. Smaller ones are invisible but noticeable by touch. Varicoceles are usually painless, though some cause a dull ache that worsens throughout the day. They can also affect fertility, so they’re worth mentioning to a doctor even if they don’t hurt.
An inguinal hernia occurs when part of the small intestine pushes through a weak spot in the tissue separating the abdomen from the groin. This can show up as a mass in the scrotum or higher up near the groin crease. Hernias tend to become more noticeable when you stand, cough, or strain.
What a Cancerous Lump Feels Like
The most common sign of testicular cancer is a painless lump on the testicle itself. These lumps can be as small as a pea or significantly larger, and they tend to feel hard or firm rather than soft and squishy. A cancerous lump is typically attached to the testicle, not floating freely in the surrounding tissue. You might also notice that one testicle has become noticeably bigger or heavier than the other, or that the texture has changed to feel unusually hard.
Testicular cancer is most frequently diagnosed in men aged 20 to 34, making it a young man’s disease. The good news is that it’s one of the most treatable cancers, especially when found early. Not every hard lump is cancer, but any new lump, nodule, or change in size or firmness warrants a prompt visit to a doctor.
Painful Lumps: Infection and Inflammation
If your lump came with pain, the cause is more likely an infection or inflammation than cancer.
Epididymitis is an inflammation of the epididymis, the coiled tube at the back of each testicle that stores and carries sperm. It typically causes a gradual onset of pain that’s localized behind the testicle and sometimes radiates to the lower abdomen. The area can feel swollen, warm, and tender. Bacterial infections, including sexually transmitted infections, are the usual trigger.
Orchitis is inflammation of the testicle itself, and it tends to come on abruptly. You’ll feel sudden scrotal pain and swelling, usually on one side. Viral infections are a common cause. Both epididymitis and orchitis are treatable, but they need medical attention to resolve properly and to rule out other causes of sudden pain.
When It’s an Emergency
Testicular torsion happens when a testicle twists on its spermatic cord, cutting off its own blood supply. This is not a lump in the traditional sense, but the testicle can swell rapidly and feel like a mass. The hallmark is sudden, severe scrotal pain, often accompanied by nausea, vomiting, abdominal pain, and sometimes fever. The affected testicle may sit higher than normal or at an unusual angle.
Torsion is a surgical emergency. When blood flow is blocked for too long, the testicle can be permanently damaged and may need to be removed. If you experience sudden, intense testicular pain, go to an emergency room immediately. Even if the pain resolves on its own, that can mean the testicle twisted and then untwisted, a pattern called intermittent torsion that tends to recur and still requires medical evaluation.
How Doctors Diagnose a Lump
A physical exam is always the starting point. Your doctor will feel the lump and the surrounding tissue to assess its size, location, and consistency. One simple test involves shining a bright light through the scrotum, a technique called transillumination. Fluid-filled masses like hydroceles and spermatoceles will glow because light passes through liquid. Solid masses, which need further evaluation, will not.
Scrotal ultrasound is the most common next step and is often needed to make a definitive diagnosis. It uses sound waves to create a detailed image showing exactly where the lump is, how large it is, and whether it’s filled with fluid or solid tissue. The test is painless and takes only a few minutes.
If there’s concern about cancer, blood tests can check for elevated levels of specific proteins associated with testicular tumors. Should cancer be confirmed, a CT scan of the chest and abdomen helps determine whether it has spread beyond the testicle.
How to Check Yourself
Monthly self-exams starting around age 15 are the best way to catch changes early. You’ll have the easiest time right after a warm shower, when the scrotal skin is relaxed. Stand up and lift the penis out of the way so you can see and feel each testicle clearly.
Gently grip the top of your scrotum and locate one testicle. Roll it slowly between your fingers, feeling for any hard lumps, nodules, or changes in size. At the top and back of each testicle, you’ll feel the epididymis, a soft, slightly squishy tube that can feel tender to the touch. This is normal anatomy, not a lump. You’ll also feel the spermatic cord connecting to the top of the testicle, which feels like a firm piece of rope. That’s normal too.
If something feels off on one side, compare it to the other testicle. Slight differences in size between the two are common and usually harmless. What you’re looking for is something new: a hard spot, a lump that wasn’t there before, or a noticeable change in how one testicle feels compared to last month. If you find anything unusual, schedule an appointment. Most lumps turn out to be benign, but the only way to know for sure is to get it checked.