Epididymal Cyst on Ultrasound on Radiology Reports: What It Means

“Epididymal cysts” are often described on a scrotal ultrasound report.  The good news is that epididymal cysts are almost always benign (non-cancerous), often painless, and commonly found by chance on ultrasound. They usually do not affect fertility or sexual function. Below is a clear explanation of what an epididymal cyst is, what it looks like on ultrasound, and when it might need treatment.

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What is an epididymal cyst?

The epididymis is a tightly coiled tube that sits on top and behind each testicle. It stores and carries sperm.

An epididymal cyst is a small, fluid-filled sac that develops in this tube. It usually feels like a smooth lump above or behind the testicle. These cysts:

1. Are filled with clear or watery fluid

2. Are benign (not cancerous)

3. Often cause no symptoms and are found incidentally

In many men and boys, epididymal cysts are discovered during a physical exam or scrotal ultrasound done for something else, such as pain or a lump.

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Scrotal Ultrasound- what the scan is looking for

A scrotal ultrasound uses sound waves to create pictures of the testicles and surrounding structures. It is painless and does not use radiation.

On ultrasound, an epididymal cyst usually looks like:

1. A round or oval black (fluid-filled) area

2. With very thin, smooth walls

3. Located in the epididymis

4. With no solid components or internal blood flow when checked with Doppler

Radiologists often call this appearance “anechoic,” meaning completely dark, with “posterior acoustic enhancement,” meaning the area behind it looks brighter because fluid transmits sound waves well.

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Epididymal cyst vs spermatocele on ultrasound

You might also see the word “spermatocele” in the report.

Both epididymal cysts and spermatoceles are:

1. Fluid-filled sacs arising from the epididymis

2. Benign

3. Extra-testicular, meaning they sit outside the testicle itself

The difference is mostly in the contents:

• Epididymal cyst:
  Fluid is clear or watery and does not contain sperm.

• Spermatocele:
  Fluid may be milky and contain sperm cells.

On ultrasound, the two look very similar, and many radiologists use the terms together. The management is usually identical for both.

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Is an epididymal cyst cancer?

No. An epididymal cyst is a benign lesion. It does not turn into testicular cancer and does not increase your risk of cancer.

However, not every lump in the scrotum is an epididymal cyst. That is why ultrasound is important. The radiologist’s main job is to:

1. Confirm that the testicle itself looks normal

2. Show that the lump arises from the epididymis and is clearly fluid-filled

3. Exclude solid or suspicious features that might suggest a tumor

Once these features are confirmed, an epididymal cyst is considered a reassuring explanation for the lump.

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Common phrases you may see on the ultrasound report

Your report may include wording such as:

• “Simple epididymal cyst”

• “Anechoic extra-testicular cyst consistent with an epididymal cyst”

• “Benign-appearing epididymal cyst / spermatocele”

• “No suspicious intra-testicular mass”

“Simple” means the cyst is filled with fluid and has smooth, thin walls. “Extra-testicular” means it arises from outside the testicle itself, which is another reassuring sign.

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Symptoms: how an epididymal cyst feels

Many epididymal cysts cause no symptoms at all. People may notice:

1. A small, smooth lump above or behind the testicle

2. A sense of fullness or heaviness in the scrotum if the cyst is large

3. Mild discomfort, pulling, or aching at times

Pain that is sudden, severe, or accompanied by nausea or a high-riding testicle is not typical of a simple epididymal cyst. That kind of pain may indicate testicular torsion or another urgent problem, which requires immediate evaluation.

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Do epididymal cysts need treatment?

Most epididymal cysts need no treatment. The usual approach is observation.

1. Medication can not shrink these cysts

2. Most stay the same size or grow very slowly

3. They rarely affect fertility

Treatment is considered when:

• The cyst becomes large or uncomfortable

• It interferes with daily activities

• There is uncertainty about the diagnosis

• It becomes cosmetically bothersome

Surgery is a common treatment when needed. A urologist can remove the cyst through a small incision, usually as an outpatient procedure.

Draining the cyst with a needle is not recommended because the fluid often returns.

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Follow-up and testicular self-exams

After an epididymal cyst is diagnosed on ultrasound, many doctors recommend simple observation. This often includes:

1. Routine follow-up with your doctor

2. Returning for evaluation if the lump changes, gets larger, or becomes painful

When to seek urgent medical care

Even if you already know you have an epididymal cyst, seek urgent care if you notice:

1. Sudden, severe testicular pain

2. A high-riding or very tender testicle

3. Redness, warmth, or fever

4. Rapid swelling of the scrotum

These symptoms are not from an epididymal cyst but could be signs of torsion or infection, which require immediate attention.

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Key points about epididymal cysts on ultrasound

1. Epididymal cysts are benign, fluid-filled sacs in the epididymis.

2. On ultrasound, they appear as smooth, dark, simple cysts outside the testicle.

3. They do not turn into cancer or affect fertility in most cases.

4. Most require no treatment; surgery is only for large or painful cysts.

5. Any new or changing scrotal lump should still be evaluated by a doctor.

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Conclusion

Seeing “epididymal cyst on ultrasound” in your radiology report is almost always a reassuring finding. It means the radiologist identified a simple, fluid-filled cyst in the epididymis and that the testicle itself appears normal. These cysts are common, benign, and typically require no treatment.  If you have concerns about symptoms, size, or any changes, a doctor can review the findings with you and determine if follow-up is needed.

References

https://patient.info/mens-health/scrotal-lumps-pain-and-swelling/epididymal-cyst

https://www.chop.edu/conditions-diseases/epididymal-cyst-and-spermatocele

https://radiopaedia.org/articles/epididymal-cyst?lang=us