What Is a Testicular Cyst and When to See a Doctor

A testicular cyst is a fluid-filled sac that forms in or around the testicle, and the vast majority are benign. Most arise not inside the testicle itself but in the epididymis, the coiled tube that sits behind each testicle and stores sperm.¹ They are extremely common, often painless, and frequently discovered by accident during an ultrasound done for an unrelated reason. Still, any new lump in the scrotum deserves a medical look, because without imaging there is no reliable way to tell a harmless cyst from something that needs treatment.

Where Scrotal Cysts Actually Form

The word “testicular cyst” gets used loosely, but the location matters. Doctors divide scrotal cysts into two broad groups: those inside the testicle and those outside it. Intratesticular cysts include simple cysts within the testicular tissue, cysts of the tunica albuginea (the tough outer shell of the testicle), and ectasia of the rete testis (a network of tiny channels inside the testicle). Extratesticular cysts include spermatoceles, hydroceles, and epididymal cysts.² In everyday conversation, people lump all of these under “testicular cyst,” but the distinction matters clinically because intratesticular lesions carry a slightly higher index of suspicion for tumor than extratesticular ones.

By far the most common type you will encounter is the epididymal cyst or spermatocele. The two terms are sometimes used interchangeably, but there is a real difference. An epididymal cyst is filled with clear fluid and contains no sperm. A spermatocele is also an epididymal cyst, but its fluid contains sperm cells, often in various stages of maturity or degeneration.³ From the outside, you cannot tell them apart. Either one feels like a small, smooth, usually painless lump sitting above or behind the testicle. The distinction only becomes clear under a microscope or on ultrasound.

How Common Are They

More common than most people realize. One study examining men referred for scrotal ultrasound found epididymal cysts in a striking 71% of participants, including both fertile and infertile men.⁴ That figure is the highest ever reported in the literature, and it likely reflects how sensitive modern ultrasound has become at picking up small cysts that a person would never notice on their own. The true prevalence in the general population is hard to pin down because most men never get a scrotal ultrasound unless something prompts one. But the broader point holds: epididymal cysts are an extremely common finding, and most are clinically insignificant.

Intratesticular cysts are less common and tend to be found incidentally. In one study of patients with both benign and cancerous testicular cysts, all 13 of the benign intratesticular cysts were discovered by accident during ultrasound. None were palpable.⁵ The cysts of the tunica albuginea, by contrast, were palpable as small hard lumps, which is one reason they sometimes trigger more anxiety.

What They Feel Like and What Causes Them

Most scrotal cysts produce no symptoms at all. When they do cause symptoms, the most common complaint is a vague sense of heaviness or fullness in the scrotum. Pain tends to be dull rather than sharp, and it often comes and goes. A large spermatocele can become noticeable enough to bother you physically, either from its size or because it creates an aching sensation after prolonged sitting or activity.

The exact cause is often unclear. Some epididymal cysts appear to result from partial blockage of the tiny tubules in the epididymis, which allows fluid to accumulate. Prior surgery in the area can be a factor: tubular ectasia of the epididymis, a pattern of multiple small cysts, shows up frequently in men who have had a vasectomy.⁶ Inguinal hernia repair and infection have also been linked. In many cases, though, no identifiable cause is found. The cyst simply develops on its own, especially as men age.

Certain congenital conditions can predispose someone to scrotal cysts early in life. Boys with cystic fibrosis, for instance, sometimes develop epididymal abnormalities including cysts, likely related to the same defect in chloride transport that affects the lungs and pancreas.⁷

When to See a Doctor

The short guidance is straightforward: any new lump in the scrotum that you have not had evaluated before warrants a visit. Most of the time, the answer will be reassuring. A large one-stop clinic study of men with testicular concerns found that about 96% had normal testes or minor abnormalities, and only around 4% turned out to have testicular cancer.⁸ Those are good odds. But you cannot distinguish the 4% from the 96% by feel alone, and catching a malignancy early makes a significant difference in outcomes.

Beyond a new lump, there are specific situations that should move you to get seen sooner rather than later:

Rapid growth: A cyst that has been stable for years and suddenly gets bigger deserves a fresh look.
Pain or tenderness: Persistent or worsening pain in a previously painless lump could mean the cyst has become complicated, or it could be something else entirely.
Firmness or irregularity: Benign cysts feel smooth and somewhat squishy. A hard, irregular mass raises the index of suspicion for tumor.
Scrotal swelling with fever: This points toward infection rather than a simple cyst and needs prompt attention.
Fertility concerns: If you are trying to conceive and have a known cyst, it is worth discussing whether it could be relevant, even though most epididymal cysts do not affect fertility.

How Doctors Tell a Cyst From Something Worse

The first step is usually a physical exam, but the real workhorse of diagnosis is scrotal ultrasound. It is painless, widely available, and very good at characterizing what a lump is made of. On ultrasound, a simple cyst appears as a well-defined, round, fluid-filled structure with thin walls and no internal blood flow. That pattern is about as close to a guarantee of benignity as imaging gets.¹

The picture gets more complicated when a cyst-like lesion has solid components, thick or irregular walls, or internal echoes suggesting something other than simple fluid. In a study comparing cancerous and benign testicular cysts, three-quarters of the malignant ones showed multiple cysts mixed with solid tissue, a pattern quite different from the solitary, cleanly defined benign cyst.⁵ Benign intratesticular cysts also tended to be single and sit near the edge of the testicle. Combining the ultrasound appearance with what the doctor feels on exam makes the distinction more reliable than either test alone.

In ambiguous cases, especially for intratesticular lesions, MRI can add further detail. Some uncommon lesions like cystic dysplasia of the rete testis require individualized follow-up over time because they sit in a gray zone where imaging alone cannot always rule out malignancy with certainty.⁹ For those, close monitoring with periodic ultrasound is the standard approach rather than immediate surgery.

Do Scrotal Cysts Affect Fertility

This is one of the most common worries men have after a cyst is found, and the evidence is reassuring. Multiple studies have now looked at whether epididymal cysts correlate with impaired sperm quality, and the answer is consistently no. In the study that found cysts in 71% of men, the presence of a cyst was not associated with infertility. The factors that were associated with infertility were smaller testicular size and the presence of a varicocele, not cysts.⁴

A more recent analysis of men undergoing fertility evaluations confirmed the finding. Neither the size of the cyst nor whether it was on one side or both sides correlated with any semen parameter, including sperm concentration, motility, and morphology.¹⁰ If you are told you have an epididymal cyst and you are concerned about having children, the cyst itself is very unlikely to be the issue.

Treatment When It Is Needed

Most cysts need no treatment. The standard recommendation is reassurance and periodic monitoring if anything changes. Treatment enters the conversation only when a cyst causes significant pain, has grown large enough to be bothersome, or in uncommon cases where there is diagnostic uncertainty that cannot be resolved by imaging alone.

Aspiration and Sclerotherapy

The least invasive option is needle aspiration, which simply drains the fluid. It is quick and inexpensive, but cysts tend to refill. To reduce recurrence, doctors sometimes follow aspiration with sclerotherapy, injecting a chemical agent into the empty cyst to make its walls stick together. One series using alcohol as the sclerosing agent reported an 85% success rate for spermatoceles and epididymal cysts after up to two procedures, with a low complication rate of about 6%.¹¹ Another study using different sclerosing agents, polidocanol and tetracycline, found that tetracycline was more effective at the nine-month mark but caused several days of post-procedure pain, while polidocanol was nearly pain-free but had a lower early cure rate. By about three years, patient satisfaction was high in both groups.¹²

Aspiration with sclerotherapy is generally reserved for older men or those who are not planning to have children, because the chemical agents used carry at least a theoretical risk of damaging the delicate epididymal tubules. A separate series found that about 89% of men with spermatoceles reported relief of bothersome scrotal fullness after aspiration and sclerotherapy, though roughly one in nine eventually needed surgical repair anyway.¹³

Surgical Removal

When surgery is needed, the standard approach is spermatocelectomy or epididymal cystectomy. Traditional techniques carry a small but real risk of damaging the epididymal tubule and causing a blockage that could impair fertility on that side. Microsurgical techniques have been developed specifically to address this concern. In a series of 23 men who underwent microsurgical spermatocelectomy, none experienced a drop in sperm count afterward, none had cyst recurrence at an average of about 17 months of follow-up, and all patients who had preoperative pain reported improvement. The most common reasons for surgery were pain and infertility, often in combination.¹⁴

A newer refinement, microscopic single-tubule spermatocelectomy, isolates the specific tubule feeding the cyst and removes only that structure. In a series of patients treated with this approach over nearly a decade, no cases of epididymal bleeding, tubule damage, cyst recurrence, or testicular atrophy occurred, and sperm motility actually improved after surgery.¹⁵ These microsurgical approaches are not available everywhere, but for younger men who want to preserve fertility, they represent a meaningful advance over older open techniques.

Scrotal Cysts in Children and Adolescents

Epididymal cysts are not exclusively an adult problem. They are found in boys as well, sometimes during ultrasound for unrelated concerns. The natural question parents have is whether the cyst will grow, cause problems, or need removal. A study following 75 children with epididymal cysts over time found that none showed a significant increase in cyst size or number during follow-up. About 12% of the cysts resolved entirely on their own, and another 6% shrank. Only a small minority, about 2%, showed any increase in size, and even those children remained symptom-free.¹⁶

The takeaway for parents is that watchful waiting is almost always the right approach in children. Surgery is rarely needed and is generally reserved for cases where a cyst grows significantly or causes discomfort. Given that epididymal cysts in boys frequently stay stable or shrink, the default management is periodic check-ups rather than any intervention.

The Anxiety Factor

Something that does not get discussed enough is how stressful finding a lump in the scrotum can be, regardless of what it turns out to be. Testicular cancer awareness campaigns have done important work, but one side effect is that many men who feel a lump immediately assume the worst. The one-stop clinic study mentioned earlier was designed specifically to address this: men with testicular anxiety could get a same-day exam and ultrasound so they were not left waiting weeks for reassurance.⁸ The vast majority walked out with a clean bill of health.

If you have found a lump and you are worried, that worry is completely reasonable. But the statistics are in your favor. Getting an ultrasound is the single most useful thing you can do, both because it nearly always provides a clear answer and because the anxiety of not knowing tends to be worse than the reality. If the lump turns out to be a simple cyst, which is the most likely outcome, the conversation shifts from “what is this” to “do I need to do anything about it,” and for most people the answer to that second question is no.

When Aspiration and Sclerotherapy Make More Sense Than Surgery

Choosing between a needle-based procedure and an operation depends on several factors. Aspiration with sclerotherapy works best for larger, symptomatic spermatoceles in men who are done having children. The procedure takes minutes, can be performed under local anesthesia, and avoids the risks of general anesthesia and surgical dissection. One early series noted each procedure cost the equivalent of roughly a hundred dollars Canadian and took under ten minutes.¹² Even when the initial attempt does not fully resolve the cyst, a repeat procedure often does, and patient satisfaction remains high.

Surgery is typically favored when fertility preservation matters, when the cyst recurs after aspiration, or when the diagnosis is uncertain and tissue is needed for pathology. Microsurgical techniques have made the operation safer from a fertility standpoint, as noted in the outcomes of both the original microsurgical spermatocelectomy series and the newer single-tubule approach.¹⁴ For younger men worried about the impact on sperm production, a microsurgical approach at a center experienced in the technique is the better bet. For older men who want relief with minimal disruption, aspiration and sclerotherapy is a reasonable first step.

Cysts That Are Not Really Cysts

Scrotal ultrasound occasionally turns up findings that look cyst-like on imaging but are actually something else. Epidermoid cysts of the testicle, for example, are classified among intratesticular cystic lesions even though they are technically solid masses made of keratinized skin cells.² They are benign, but because they can mimic tumor on imaging, they sometimes lead to unnecessary worry or even surgery before a definitive diagnosis is reached. Testicular abscesses and areas of infarction can also create cyst-like appearances on ultrasound, though these tend to present with more acute symptoms like pain, swelling, and fever.

Varicoceles, which are dilated veins in the scrotum, occasionally get lumped into the “cyst” conversation as well because they can feel like soft lumps. They are not cysts at all but are worth mentioning because they are one of the few scrotal findings that do consistently correlate with reduced fertility, unlike true epididymal cysts. If your ultrasound report mentions a varicocele alongside a cyst, the varicocele may actually be the more clinically relevant finding, especially if fertility is a concern.⁴