Finding a lump in your scrotum is understandably worrying. One of the most common causes is an epididymal cyst, a small, fluid-filled swelling that is almost always harmless. This guide explains what epididymal cysts are, what causes them, how they are diagnosed and when they need treatment. Most importantly, it explains why any new lump should be examined by a doctor rather than self-diagnosed.
What is an epididymal cyst?
The epididymis is a tightly coiled tube that sits on top of and behind each testicle. It stores sperm and carries it towards the vas deferens. An epididymal cyst is a smooth, fluid-filled sac that develops within this tube.
A cyst that contains sperm is sometimes called a spermatocele. In practice, the two look and behave the same way and are managed in the same way.
Epididymal cysts are benign (not cancerous). They are common, particularly from middle age onwards. You may have one cyst or several, on one or both sides.
What causes epididymal cysts?
In most men there is no identifiable cause. Cysts are thought to form when part of the epididymis becomes blocked or widened, allowing fluid to collect.
It can help to know what does not cause them:
- They are not caused by masturbation or sexual activity.
- They are not a sexually transmitted infection and cannot be passed to a partner.
- They are not a form of cancer and do not turn into cancer.
Rarely, multiple cystic lumps in the epididymis are associated with inherited conditions such as von Hippel–Lindau disease. Your doctor will ask about your family history if this seems relevant.
Symptoms
Many epididymal cysts cause no symptoms and are found by chance, during self-examination or a scan for something else. When symptoms occur, they typically include:
- a smooth, round lump, usually above or behind the testicle and separate from it;
- a feeling of heaviness or a dull ache, usually only when the cyst is large;
- occasional discomfort, for example when sitting or exercising.
Most cysts grow slowly, if at all.
Is it a cyst or something more serious?
You cannot reliably tell lumps apart yourself, which is why every new scrotal lump should be checked by a doctor. Other causes of scrotal swelling include a hydrocele (fluid around the testicle), a varicocele (enlarged veins), an inguinal hernia, infection (epididymitis) and, less commonly, testicular cancer. Testicular cancer usually causes a firm lump within the testicle itself and is most common in men aged 15 to 49. For an overview, see our guide to common causes of testicular lumps and swellings.
Seek urgent medical help (A&E or 999) if you have sudden, severe pain or swelling in a testicle, especially with nausea or vomiting. This can be testicular torsion, which needs emergency treatment.
How is an epididymal cyst diagnosed?
- Examination. A specialist feels the lump to confirm whether it is separate from the testicle. Shining a light through the scrotum (transillumination) can show that it is filled with fluid.
- Scrotal ultrasound. This painless scan confirms a fluid-filled cyst, shows exactly where it sits and checks that the testicle itself is normal. Ultrasound is the standard test for any uncertain scrotal lump.
Does an epididymal cyst need treatment?
Most do not. If a cyst is small and painless and the scan is reassuring, the usual advice is to leave it alone and keep an eye on it. Many men live with an epididymal cyst for years without problems.
Treatment may be considered if a cyst is painful, large enough to be bothersome, growing, or affecting your quality of life.
Surgical removal
The definitive treatment is surgical removal (epididymal cystectomy or spermatocelectomy). It is usually a day-case procedure under general anaesthetic, through a small cut in the scrotum. Risks to discuss with your surgeon include:
- bruising, swelling or a collection of blood (haematoma);
- wound infection;
- the cyst coming back;
- ongoing scrotal discomfort in a small number of men (see chronic scrotal and testicular pain);
- damage to the epididymis, which can block the passage of sperm on that side.
Because of this last risk, men who are planning to have children should discuss fertility carefully before choosing surgery. Leaving a harmless cyst alone is often the better option for younger men. See also the causes of male sub-fertility.
Draining the cyst with a needle (aspiration) is occasionally used, but cysts often refill afterwards, so it is less commonly recommended.
When to see a specialist
Arrange an assessment if you notice any new lump or swelling, a known cyst grows or becomes painful, you feel a firm lump in the testicle itself, or you are simply worried. A prompt examination and ultrasound usually give a clear answer quickly, and in most cases that answer is reassuring.
Frequently asked questions
Are epididymal cysts cancerous?
No. They are benign and do not turn into cancer. Any new lump should still be examined, and usually scanned, to confirm the diagnosis.
Can an epididymal cyst go away on its own?
Some shrink, but many stay the same size for years. A cyst causing no symptoms usually needs no treatment.
Do epididymal cysts affect fertility?
The cyst itself does not usually affect fertility. Surgery to remove it can sometimes block sperm transport on that side, so men planning a family should discuss this first.
Can I exercise or have sex with an epididymal cyst?
Yes. Supportive underwear may help if a larger cyst causes aching.
How do I arrange an assessment?
Book a free phone call with our team, or message us on WhatsApp at +44 7457 404374.
References
- NHS. Epididymal cyst. nhs.uk.
- NICE Clinical Knowledge Summaries. Scrotal swellings. cks.nice.org.uk.
- Rubenstein RA, Dogra VS, Seftel AD, Resnick MI. Benign intrascrotal lesions. J Urol. 2004;171(5):1765–1772.
- European Association of Urology. EAU Guidelines on Testicular Cancer. Current edition.
This article is for educational purposes only and does not constitute personal medical advice. All treatment decisions should follow consultation with a qualified professional.
