Can an Epididymal Cyst Be Cancerous?
Finding a lump near your testicle can be worrying, and one of the first questions many men ask is: could this be cancer?
The reassuring answer is that a correctly diagnosed epididymal cyst is benign (non-cancerous) and is not considered a precancerous condition.[1,3-6] It does not normally “turn into” testicular cancer.
However, it is important not to assume that every lump beside a testicle is an epididymal cyst. A new lump should be properly assessed because testicular tumours and, much less commonly, other paratesticular tumours can sometimes present in the same general area.[1-4]
If you have already been told you have an epididymal cyst, you can read more about epididymal cysts and spermatoceles.
What is an epididymal cyst?
The epididymis is a coiled tube that sits above and behind each testicle. It stores and transports sperm.
An epididymal cyst is a small sac of fluid that develops within or next to the epididymis. On ultrasound, a typical simple cyst appears as a well-defined, thin-walled, fluid-filled structure without internal blood flow.[4-7]
A spermatocele is closely related. It is also a cyst arising from the epididymis, but its fluid contains sperm. From a patient's point of view, epididymal cysts and spermatoceles can feel very similar and are often managed in the same way.[4,5]
They are common findings and many cause no symptoms at all.[4-6]
So, can an epididymal cyst be cancer?
A simple epididymal cyst itself is not cancer.
When imaging confidently demonstrates a typical simple epididymal cyst, this is considered a benign condition.[4-7]
The important distinction is between:
a simple fluid-filled epididymal cyst, and
a solid or unusual mass involving the epididymis, testicle or surrounding tissues.
Those are not the same diagnosis.
Most masses arising outside the testicle are benign, but rare cancers can occur in the epididymis, spermatic cord or other tissues around the testicle.[3,4,7]
One study examining solid epididymal masses found that 94% were benign and 6% were malignant.[3] Importantly, this study involved solid or complex epididymal masses rather than typical simple epididymal cysts, so the 6% figure should not be applied to someone whose ultrasound has confirmed a straightforward fluid-filled cyst.
Why does the location of the lump matter?
One of the most important questions when assessing a scrotal lump is:
Is the lump inside the testicle or outside it?
This matters because testicular germ-cell cancers usually arise within the testicle itself, whereas common epididymal cysts arise outside the testicle.[1,2,4]
Current European Association of Urology guidance recommends high-frequency testicular ultrasound when evaluating a suspected testicular mass. Ultrasound helps determine whether an abnormality is intratesticular or extratesticular and assesses its size, location and characteristics.[1]
You can read more about the broader assessment of scrotal and testicular conditions.
How can ultrasound tell the difference?
A scrotal ultrasound is particularly useful because it can usually identify both where a lump is located and whether it is fluid-filled or solid.[1,2,4-7]
A typical epididymal cyst often appears:
round or oval
smooth and well defined
filled with fluid
separate from the testicular tissue
without internal blood flow on Doppler ultrasound.[4-6]
A suspicious testicular tumour is more commonly a solid intratesticular lesion, often with internal blood flow, although imaging appearances vary and ultrasound alone cannot determine every diagnosis with complete certainty.[1,2]
If ultrasound findings are genuinely indeterminate, further specialist assessment, repeat imaging or occasionally MRI may be considered depending on the circumstances.[1,7]
What if the lump feels hard?
How a lump feels can provide useful information, but you cannot reliably diagnose a scrotal lump by touch alone.
An epididymal cyst often feels smooth and separate from the testicle. A hard area that appears to be within the testicle itself, rather than behind or above it, deserves prompt assessment.
You should arrange medical review if you notice:
a new lump in or around a testicle
an area of new firmness within the testicle
enlargement or a change in the shape of a testicle
a lump that seems to be getting larger
persistent unexplained scrotal swelling or heaviness
an ultrasound report describing a solid, vascular, indeterminate or intratesticular lesion.
These findings do not automatically mean cancer, but they should not be assumed to represent a harmless cyst.
For more information, see testicular cancer and testicular mass assessment.
Can cancers occur beside the testicle?
Yes, but they are uncommon.
A mass arising outside the testicle is described as extratesticular or paratesticular. These masses may arise from the epididymis, spermatic cord, tunica or other tissues surrounding the testicle.
Most extratesticular masses are benign, particularly when typical epididymal cysts and spermatoceles are included.[3,4] Less commonly, solid paratesticular tumours can be malignant and may require a different investigation and surgical pathway.
If an ultrasound describes a solid paratesticular mass rather than an epididymal cyst, further assessment may therefore be appropriate.
Read more about paratesticular tumours and masses.
Does an epididymal cyst need to be removed?
Usually, no.
If the diagnosis is clear and the cyst is not causing significant symptoms, observation is often reasonable.[4-6]
Surgery may be considered when a cyst causes troublesome:
discomfort or aching
heaviness
mechanical symptoms
progressive enlargement
interference with exercise or daily activities.
There is no single cyst size that automatically requires surgery. The decision depends on symptoms, examination findings, diagnostic certainty, fertility considerations and the balance between potential benefits and risks.
More information about treatment is available on the Epididymal Cyst & Spermatocele page.
What about fertility?
The cyst itself usually has little or no effect on fertility.
Surgery is a separate issue because the epididymis forms part of the pathway that transports sperm. Removing a cyst can potentially cause scarring or obstruction of the epididymis.
This may be particularly relevant if:
cysts are present on both sides
you have previously had scrotal or epididymal surgery
you already have reduced fertility
you have not completed your family.
If fertility is a concern, it is worth discussing this before proceeding with elective epididymal surgery. You can also explore male fertility assessment and treatment.
Can I ignore a lump if someone previously told me it was a cyst?
A previously confirmed cyst that has remained unchanged may not require treatment.
However, reassessment is sensible if:
the lump has clearly enlarged or changed
it feels different from previously
you develop new persistent symptoms
you can now feel another lump
you are unsure whether the lump is actually the previously diagnosed cyst.
A previous benign diagnosis should not automatically be assumed to explain every new scrotal change.
What if I develop sudden severe pain?
Sudden severe testicular or scrotal pain requires urgent medical assessment.
Testicular torsion is a different condition in which the blood supply to the testicle becomes twisted. It can require urgent surgery and should not be assumed to be pain from an epididymal cyst.
Seek urgent care particularly if severe pain is associated with nausea, vomiting, rapid swelling or a change in the position of the testicle.
Take home message
A confirmed simple epididymal cyst is benign and is not expected to become cancerous.
The important step is making sure that a new scrotal lump really is an epididymal cyst rather than a lump arising within the testicle or another type of paratesticular mass.
Examination and, when appropriate, scrotal ultrasound can usually clarify the difference.
If you have found a new lump or have an ultrasound result that you would like assessed, you can request an appointment.
References
European Association of Urology. EAU Guidelines on Testicular Cancer. Arnhem: EAU Guidelines Office; 2026.
Stephenson A, Bass EB, Bixler BR, Daneshmand S, Kirkby E, Marianes A, et al. Diagnosis and treatment of early-stage testicular cancer: AUA guideline amendment 2023. J Urol. 2024;211(1):20-25. doi:10.1097/JU.0000000000003694.
Alleman WG, Gorman B, King BF, Larson DR, Cheville JC, Nehra A. Benign and malignant epididymal masses evaluated with scrotal sonography: clinical and pathologic review of 85 patients. J Ultrasound Med. 2008;27(8):1195-1202. doi:10.7863/jum.2008.27.8.1195.
Gabriel H, Hammond NA, Marquez RA, Vendrami CL, Horowitz JM, Casalino DD, et al. Gamut of extratesticular scrotal masses: anatomic approach to sonographic differential diagnosis. Radiographics. 2023;43(4):e220113. doi:10.1148/rg.220113.
Cheung JLS, Bhaduri M. A sound approach to stay on the ball—a review of scrotal pathologies on ultrasound imaging. Br J Radiol. 2026;99(1181):847-858. doi:10.1093/bjr/tqag063.
Kühn AL, Scortegagna E, Nowitzki KM, Kim YH. Ultrasonography of the scrotum in adults. Ultrasonography. 2016;35(3):180-197. doi:10.14366/usg.15075.
Smart JM, Jackson EK, Redman SL, Rutherford EE, Dewbury KC. Ultrasound findings of masses of the paratesticular space. Clin Radiol. 2008;63(8):929-938. doi:10.1016/j.crad.2007.09.004.
Medical disclaimer
This information is provided for general educational purposes only and does not replace individual medical advice, examination or diagnosis. A new or changing scrotal or testicular lump should be assessed by an appropriately qualified healthcare professional. Individual investigations and treatment recommendations depend on examination findings, imaging, symptoms, fertility goals and other clinical circumstances. Sudden severe testicular pain requires urgent medical assessment.
