A lump on your testicle is usually benign, but it always warrants a medical evaluation because testicular cancer also presents as a lump, often painless. The most common causes are fluid-filled cysts, enlarged veins, and infections, all of which are noncancerous. Still, the only reliable way to tell the difference is with an ultrasound.
The Most Common Benign Causes
Several conditions can create a noticeable lump or swelling in the scrotum without any cancer involvement.
A spermatocele is a fluid-filled sac that develops near the top of the testicle, in the small coiled tube (the epididymis) that stores and transports sperm. These are typically painless and feel like a smooth, rounded bump separate from the testicle itself. Many men discover them incidentally and never need treatment.
A hydrocele is a collection of fluid in the thin sheath surrounding the testicle. It causes general swelling rather than a discrete hard lump. Hydroceles are painless and benign, though large ones can feel heavy or uncomfortable.
A varicocele is an enlargement of the veins inside the scrotum, similar to varicose veins in the legs. Rather than feeling like a firm lump, a varicocele often has a soft, irregular texture sometimes described as feeling like a bag of spaghetti. Varicoceles are usually painless, though they can cause a dull ache that comes and goes. They’re worth knowing about because they contribute to roughly 40% of male infertility cases. The buildup of blood in the veins may raise the temperature inside the scrotum enough to affect sperm production.
Less commonly, an inguinal hernia can push a loop of intestine into the scrotum, creating a lump that may change size when you stand, cough, or lie down. Infections of the testicle or epididymis also cause swelling, but these typically come with pain, warmth, and sometimes fever.
When a Lump Could Be Cancer
Testicular cancer often shows up as a painless, hard lump or swelling on the testicle itself. That’s the key distinction: benign cysts and varicoceles tend to sit near or around the testicle, while cancerous masses are usually embedded in the testicular tissue. Some testicular cancers cause discomfort, but many produce no pain at all, which is why a painless lump should never be dismissed as “nothing.”
The median age at diagnosis for testicular cancer is 33, and over half of all cases occur in men between 20 and 34. Another quarter are diagnosed between 35 and 44. This makes it primarily a young man’s disease, though it can occur at any age. A history of an undescended testicle or a family history of testicular cancer increases risk.
One study of small testicular lesions (under 20 mm) found that 69% turned out to be malignant. Even among the smallest lesions, those under 10 mm, about 61% were cancerous. These numbers come from patients who were already flagged for further evaluation, so they don’t represent every lump found in every man. But they underscore why any solid mass within the testicle needs prompt investigation.
How Doctors Figure Out What It Is
The first step is a physical exam, but the real diagnostic workhorse is a scrotal ultrasound. This painless imaging test uses sound waves to distinguish between fluid-filled cysts and solid masses. A simple cyst filled with clear fluid has a characteristic appearance that’s easy to identify. Solid masses show different patterns: cancerous tumors like seminomas typically appear as dense, dark masses, while benign growths like fibromas have a brighter, well-defined appearance. Blood flow patterns within the mass also help, since some benign lesions show no blood flow while many tumors do.
If the ultrasound raises suspicion of cancer, blood tests measure specific proteins that certain testicular tumors release. These markers help confirm the diagnosis, determine the tumor type, and guide treatment planning. Importantly, doctors obtain these blood draws before any surgical procedure so they have a baseline to track afterward.
What a Self-Exam Looks Like
Checking your own testicles takes about a minute and is easiest during or after a warm shower, when the scrotal skin is relaxed. Stand in front of a mirror, hold your penis out of the way, and examine the skin of the scrotum for any visible swelling. Then use both hands to examine each testicle individually: place your index and middle fingers underneath and your thumbs on top, and gently roll the testicle between them.
You’re feeling for hard lumps, smooth rounded bumps, or any change in size, shape, or firmness compared to how the testicle normally feels. It’s normal to feel the epididymis as a soft, tube-like structure along the back and top of each testicle. What you’re looking for is something new, something that wasn’t there before or that feels distinctly different from the surrounding tissue. If you find anything unusual, have it evaluated. Most lumps turn out to be harmless, but the ones that aren’t are highly treatable when caught early.
Testicular Torsion: The Emergency to Know About
Not every scrotal problem presents as a slow-growing lump. Testicular torsion happens when the spermatic cord twists, cutting off blood supply to the testicle. It causes sudden, severe pain, swelling, and sometimes nausea or vomiting. This is a surgical emergency. The testicle can be saved if blood flow is restored within a few hours, but delays risk permanent damage. If you experience sudden intense testicular pain, get to an emergency room immediately, don’t wait to see if it improves.