What Is an Epididymal Cyst and How Is It Treated?

An epididymal cyst is a fluid-filled sac that forms in the epididymis, the coiled tube sitting behind each testicle that stores and transports sperm. These cysts are benign, meaning they are not cancerous and do not become cancerous. Most are small, painless, and discovered by accident during a physical exam or an ultrasound done for another reason. Treatment ranges from doing nothing at all to surgical removal, depending almost entirely on whether the cyst causes discomfort or anxiety.

Where Epididymal Cysts Come From

The epididymis is a tightly wound duct system connecting the testicle to the vas deferens. Its job is to collect newly made sperm, let them mature, and funnel them onward. An epididymal cyst develops when part of this duct system balloons out and fills with clear fluid. Research on the fluid inside these cysts suggests they are continuous with the rete testis, likely forming as dilations of the small efferent ducts or a remnant duct called Haller’s superior aberrant duct.¹ In plain terms, the plumbing backs up or pockets off in a spot where fluid collects and has nowhere to go.

Nobody knows exactly why this happens in most cases. There is no single trigger. Most epididymal cysts appear spontaneously in adult men, often in middle age, and many men have more than one. They can occur on one side or both. Because the epididymis is outside the testicle itself, these cysts are classified as extratesticular, which immediately puts them in a lower-risk category from a diagnostic standpoint.

Epididymal Cysts Versus Spermatoceles

You will often see these two terms used almost interchangeably, but they are technically different. An epididymal cyst contains clear, watery fluid with no sperm cells. A spermatocele contains cloudy or milky fluid that includes sperm, often dead or degenerating. Lab analysis of the fluid shows that spermatoceles have higher concentrations of certain inflammatory signaling molecules compared to epididymal cysts, though neither type contains actual inflammatory cells like the white blood cells you would see in an infection.²

From a practical standpoint, the distinction rarely changes what you or your doctor do about it. On ultrasound, both look the same: well-defined, round, fluid-filled masses that let sound waves pass through easily.³ The only reliable way to tell them apart is to analyze the aspirated fluid under a microscope. Since the treatment approach is the same for both, most clinicians group them together and move on.

What They Feel Like

Most epididymal cysts cause no symptoms whatsoever. When they do produce symptoms, the most common complaint is a dull ache or a sense of heaviness in the scrotum, especially when the cyst has grown large enough to press on surrounding structures. You might notice a smooth, round lump above or behind the testicle that moves freely when you touch it and feels distinctly separate from the testicle itself. That separateness is a helpful clue: lumps within the testicle are a bigger concern than lumps next to it.

In a study of 51 men who had microsurgical removal of epididymal cystic lesions, about two-thirds reported palpable pain over the cyst before surgery.⁴ That said, this was a surgical population, men who had already been referred because their cysts were bothersome. In the broader population, the majority of cysts are found incidentally during imaging or examination and never cause trouble.

How They Are Diagnosed

The standard diagnostic tool is scrotal ultrasound. It is quick, painless, widely available, and extremely good at distinguishing fluid-filled cysts from solid masses. On ultrasound, an epididymal cyst appears as a dark (anechoic), sharply outlined pocket with bright echoes behind it, a telltale sign of fluid. Larger cysts may have internal walls or septations and can occasionally be mistaken for a hydrocele, which is a different type of fluid collection that surrounds the testicle rather than sitting beside it.³

One of the most important roles of ultrasound is ruling out something more serious. In a study of 610 men who were referred with what clinicians believed to be epididymal disease and no suspicion of cancer, ultrasound uncovered unsuspected testicular tumors in eight of them, seven of which were malignant.⁵ Those odds are low, but the finding underscores why a lump in the scrotal area deserves an ultrasound rather than a guess. The imaging had a sensitivity of about 98% and specificity near 100% for catching testicular cancer in that group.

The Anxiety Factor

Finding a lump near your testicle is alarming. The immediate fear for most men is cancer, which is understandable given how much public health messaging focuses on testicular self-examination. Research from a one-stop clinic for men with testicular anxiety confirmed that lumps and scrotal pain both cause substantial worry, almost always tied to concerns about possible malignancy.⁶

The reassuring reality is that epididymal cysts are among the most common benign findings on scrotal ultrasound. They are extratesticular, and the vast majority of testicular cancers arise inside the testicle, not in the epididymis. Once ultrasound confirms a simple cyst outside the testicle, the cancer question is effectively off the table. For many men, that reassurance alone is the only “treatment” needed.

When No Treatment Is the Right Treatment

Most epididymal cysts require no intervention. If the cyst is small, painless, and not growing quickly, the standard recommendation is watchful waiting. You live with it, check it periodically, and only revisit the question if something changes. Many cysts stay the same size for years. Some even shrink on their own, particularly in younger patients. A case report of bilateral epididymal cysts in a child documented spontaneous resolution over a period of up to 50 months with no surgery required.⁷

The decision to treat is driven by symptoms, not by the mere presence of a cyst. A man with a painless cyst he only knows about because of an ultrasound has no medical reason to pursue surgery. Treatment is reserved for cysts that cause persistent pain, significant discomfort during physical activity, or enough distress that the man wants it dealt with.

Aspiration and Sclerotherapy

For men who want relief without full surgery, aspiration is an option. The procedure involves inserting a needle into the cyst under ultrasound guidance and draining the fluid. It is quick, can be done under local anesthesia, and provides immediate relief. The catch is that many cysts refill. Aspiration alone has a high recurrence rate because the cyst wall remains intact and continues to produce fluid.

To reduce recurrence, doctors sometimes follow aspiration with sclerotherapy, injecting an irritating agent (often alcohol) into the emptied cyst. The idea is to inflame the cyst lining so it scars shut and stops producing fluid. One study using 100% alcohol found that about 74% of spermatoceles and epididymal cysts resolved after a single procedure. For those that did not, a second round brought the overall success rate to 85% at a median follow-up of roughly two and a half years, with a complication rate of about 6%.⁸ A separate long-term study reported an initial success rate of 76% that climbed to 94% with repeated treatments.⁹

Sclerotherapy is generally considered a reasonable option for older men or those who are not concerned about future fertility. In younger men, there is some concern that the sclerosing agent could damage the delicate epididymal tubules and impair sperm transport, though data on this risk are limited. For that reason, many urologists steer younger patients toward surgical excision if intervention is needed.

Surgical Removal

Surgery, usually called epididymal cystectomy or spermatocelectomy, is the most definitive treatment. The traditional approach involves a small incision in the scrotum, identifying the cyst, and excising it while preserving as much of the surrounding epididymal tissue as possible. A newer microsurgical technique uses an operating microscope to dissect the cyst away from the epididymal tubules with greater precision.

The microsurgical approach has shown promising results for younger men worried about fertility. In a study of 51 men who underwent microsurgical cystectomy, pain disappeared in about 80% of patients after surgery. The complication rate was roughly 7%, and no cyst recurrence was observed during follow-up. Perhaps most importantly for the fertility question, there was no significant change in sperm count, motility, or morphology at one year after surgery. Men whose cysts were larger than 2.5 cm actually saw improvements in sperm count after removal, likely because the cyst had been compressing the epididymal ducts and obstructing sperm flow.⁴

Research using microscopic techniques also suggests there may be a size threshold to keep in mind. One team recommended that surgery be carried out before a cyst grows beyond about 0.8 cm in diameter, arguing that larger cysts risk destroying all the tubules in the affected part of the epididymis, which could permanently damage the sperm transport network on that side.¹⁰ This is a relatively aggressive stance compared to the more common “wait and see” approach, and it applies mainly to men for whom preserving fertility on that side is a priority.

Complications of Surgery

Like any scrotal procedure, cystectomy carries a small risk of complications. A large review of elective benign scrotal surgeries found overall complication rates that included hematoma in about 9%, infection in 5%, recurrence of the swelling in about 7%, and chronic pain in a very small fraction of cases.¹¹ Most of these complications are self-limiting; hematomas resolve, infections respond to antibiotics, and recurrence can be managed with a repeat procedure. Chronic pain after scrotal surgery is rare but real, and it is the complication that worries surgeons the most because it can be difficult to treat once established.

The recurrence figure deserves a note. Traditional open excision has a somewhat higher recurrence rate than microsurgical techniques because the surgeon is working without magnification and may leave behind a fragment of cyst wall. Microsurgical excision, where available, appears to reduce both recurrence and collateral damage to the epididymis, though it requires specialized training and equipment that not every hospital offers.

Epididymal Cysts in Children

Epididymal cysts are not exclusively an adult problem. Studies estimate their incidence in the pediatric age group at somewhere between 5% and 20%, depending on how they are detected.¹² In children, these cysts can cause scrotal pain that mimics more urgent conditions like testicular torsion, which is why ultrasound is especially valuable in pediatric cases to quickly sort out what is happening.

The good news is that spontaneous resolution is more common in children than in adults. As noted earlier, documented cases show cysts disappearing on their own over months to years without any intervention.⁷ Pediatric urologists tend to take a conservative approach, recommending observation and reassurance for the child and parents, reserving surgery for cases where the cyst is large, persistently symptomatic, or failing to resolve over a reasonable period.

Links to Genetic Conditions

The vast majority of epididymal cysts are isolated, random findings with no deeper medical significance. However, there is one notable genetic association. Von Hippel-Lindau (VHL) disease, a hereditary condition that predisposes people to tumors and cysts in multiple organs, can produce a specific type of epididymal growth called a papillary cystadenoma. These are benign tumors rather than simple cysts, though they arise in the same anatomical neighborhood. Epididymal cystadenomas are frequently found in men with VHL and can sometimes be bilateral.¹³

In most VHL patients, these epididymal lesions are asymptomatic and managed conservatively. A case report described an unusual presentation in a 27-year-old man with a known VHL history who developed recurrent blood in his semen from bilateral epididymal cystadenomas, ultimately requiring surgical removal of both epididymides.¹⁴ For a man with no personal or family history of VHL, a solitary epididymal cyst does not raise concern for the condition. But bilateral or unusual-appearing epididymal masses in a young man, especially with a family history of VHL-related tumors, may warrant further investigation.

Environmental Exposures and Epididymal Cysts

One environmental link worth knowing about involves diethylstilbestrol (DES), a synthetic estrogen prescribed to millions of pregnant women from the 1940s through the early 1970s to prevent miscarriage. It was later found to cause reproductive abnormalities in the children exposed in the womb. Among men whose mothers took DES during pregnancy, epididymal cysts and underdeveloped testes were found in about 32%, compared to roughly 8% of men whose mothers received a placebo.¹⁵

A later cohort study refined these numbers and found the relative risk of epididymal cyst in DES-exposed men was about 2.5 times that of unexposed men. When DES exposure began before the 11th week of pregnancy, the risk rose to roughly 3.5 times that of controls.¹⁶ DES was banned in pregnancy decades ago, so this exposure is relevant mainly to men born before the mid-1970s. Still, the DES story is a clear example of how hormonal disruption during fetal development can shape the anatomy of the reproductive tract in ways that persist into adulthood, including the formation of epididymal cysts.

Fertility Concerns

Men who learn they have an epididymal cyst often worry about whether it could affect their ability to have children. For most small cysts, the answer is no. A cyst sitting on the surface of the epididymis does not typically block the internal duct, so sperm continue to pass through normally. The concern grows when a cyst becomes large enough to compress or obstruct the epididymal lumen, the narrow channel sperm travel through. Even then, the effect is usually limited to one side, and the other testicle continues to function normally.

Ironically, it is sometimes the treatment rather than the cyst itself that poses the greater threat to fertility. Traditional open surgery risks inadvertently damaging the epididymal tubules, potentially blocking sperm transport on that side. Sclerotherapy agents can scar the duct lining. This is why the microsurgical approach is increasingly preferred for younger men: it preserves the tubules more reliably. The surgical data cited earlier showed no decline in sperm parameters after microsurgical removal, and men with large cysts over 2.5 cm actually saw sperm counts improve.⁴ If you are a younger man considering treatment for an epididymal cyst and fertility matters to you, asking specifically about microsurgical techniques is worth the conversation.

Can Epididymal Cysts Come Back

Recurrence depends heavily on the treatment method. Simple aspiration has the highest recurrence rate because the cyst wall is left intact. Sclerotherapy reduces recurrence but does not eliminate it; some men need more than one session to achieve lasting results. Surgical excision has the lowest recurrence rate, especially with microsurgical techniques where the entire cyst wall is carefully removed under magnification. The study of benign scrotal surgery reported swelling recurrence in about 7% of cases across all types of scrotal procedures, including cystectomy.¹¹

A new cyst can also form in a different part of the epididymis, which is not technically a recurrence but may feel like one. Men who are prone to forming these cysts sometimes develop new ones over the years. There is no proven way to prevent epididymal cysts from forming in the first place, so the management strategy remains the same each time: assess whether it bothers you, and treat only if it does.

1
PubMed. Composition of fluids obtained from human epididymal cysts
2
PubMed. Pro-inflammatory cytokine response of the fluid contents of spermatoceles and epididymal cysts
3
European Society of Radiology. Sonographic findings of epididymal masses
4
PubMed. Microsurgical Epididymal Cystectomy does not Impact Upon Sperm Count, Motility or Morphology and is a Safe and Effective Treatment for Epididymal Cystic Lesions (ECLs) in Young Men With Fertility Requirements
5
PubMed. Ultrasound diagnosis of testicular tumours presenting as epididymal disease
6
PubMed Central. A one-stop clinic for men with testicular anxiety
7
PubMed Central. Bilateral epididymal cyst with spontaneous resolution
8
PubMed. Aspiration and sclerotherapy of hydroceles and spermatoceles/epididymal cysts with 100% alcohol
9
PubMed. Long-term experience with sclerotherapy for treatment of epididymal cyst and hydrocele
10
PubMed. Microscopic Cyst Resection for the Treatment of Patients Diagnosed with Epididymal Cyst
11
PubMed. Complications and risk factors in elective benign scrotal surgery
12
Journal of Pediatric Surgery Case Reports. Epididymal cyst: An etiology of scrotal pain in children
13
PubMed. Epididymal cystadenomas in von Hippel-Lindau disease
14
Urology Case Reports. VON Hippel-Lindau syndrome: A rare case of epididymal cystadenoma associated with hemospermia
15
PubMed. Association of diethylstilbestrol exposure in utero with cryptorchidism, testicular hypoplasia and semen abnormalities
16
PubMed Central. Urogenital abnormalities in men exposed to diethylstilbestrol in utero: a cohort study