A lump in the scrotum

What are the common causes of scrotal lumps and swelling?

Common possibilities include:

• epididymal cyst or spermatocele — a benign fluid-filled cyst arising from the epididymis;
• hydrocele — fluid collecting around the testicle;
• varicocele — enlarged veins around the testicle;
• epididymitis or epididymo-orchitis — inflammation or infection;
• inguinal hernia — bowel or tissue descending into the groin/scrotum;
• testicular tumour;
• testicular torsion — twisting of the spermatic cord, usually presenting with sudden pain rather than a chronic lump.

A clinical review of scrotal masses emphasises this broad differential and the importance of distinguishing painful emergencies from painless swellings.¹

Are most scrotal lumps cancer?

No.

Many lumps outside the testicle are benign. Hydroceles, varicoceles and epididymal cysts are common examples.

But a new intratesticular lump deserves prompt assessment because testicular cancer often presents as a unilateral mass or enlargement.¹

This is why reassurance should come from identifying what the lump actually is—not from assuming that most lumps are benign.

What does a cancerous testicular lump usually feel like?

Classically, testicular cancer may present as:

• a new firm or hard area within the testicle;
• enlargement of one testicle;
• a painless lump;
• a feeling of heaviness.

However, pain does not rule cancer out.

A UK primary-care case-control study analysed 1,398 testicular-cancer cases and 4,956 matched controls.² The features most strongly associated with cancer included testicular swelling, testicular lump and scrotal swelling.²

Among men aged 17–49, the positive predictive value (PPV) of a recorded testicular lump was 2.5% (95% CI 1.1–5.6%).²

That means the majority of men presenting with a lump did not have testicular cancer—but the risk was high enough to justify investigation.

When a testicular lump occurred together with testicular swelling or pain, the PPV increased substantially in that study.²

Does pain make cancer unlikely?

Not reliably.

Traditional teaching often describes testicular cancer as painless, but the UK study found that painful testicular enlargement can also be associated with malignancy.²

Painful swelling has many benign causes, especially infection, but pain should not be used as a reason to ignore a new persistent testicular change.

What is an epididymal cyst?

The epididymis is a soft tubular structure behind and above the testicle. Cysts arising from it are common and usually benign.

They may feel like a smooth, mobile lump separate from the testicle itself. If the diagnosis is uncertain on examination, ultrasound can usually distinguish a cystic epididymal lesion from a solid intratesticular mass.

What is a hydrocele?

A hydrocele is a collection of fluid around the testicle. It can cause one side of the scrotum to enlarge smoothly and may be painless.¹

Most adult hydroceles are benign, but a very large hydrocele can make the underlying testicle difficult to examine. If the testis cannot be adequately assessed or the diagnosis is uncertain, ultrasound is useful.

What is a varicocele?

A varicocele is enlargement of veins in the spermatic cord, more commonly on the left side. It may feel like a “bag of worms”, become more obvious when standing and sometimes cause an ache or heaviness.¹

Varicoceles can also be relevant to male fertility in selected men.

Why is ultrasound so important?

High-resolution scrotal ultrasound can usually answer several key questions:

• Is the lesion inside or outside the testicle?
• Is it solid or fluid-filled?
• Is blood flow normal?
• Are there features suggesting inflammation, torsion or tumour?

Ultrasound is the main imaging test for an uncertain scrotal mass.^{1, 3}

I have heard that most small testicular lesions are benign. Is that true?

This needs careful context.

A European radiology review reported that up to 80% of small, incidentally discovered solid testicular lesions detected on ultrasound were benign in the literature it reviewed.³

That is reassuring—but it applies mainly to small, non-palpable lesions found incidentally on imaging, often during scans performed for another reason.³

It should not be misquoted as “80% of testicular lumps are harmless.” A palpable, firm intratesticular mass is a different clinical situation.

Will every suspicious lesion mean removal of the testicle?

Not necessarily, although a clearly suspicious intratesticular mass is treated seriously.

Management depends on ultrasound appearance, tumour markers, lesion size, whether the mass is palpable and overall clinical context. Very small incidental lesions may sometimes be suitable for surveillance or testis-sparing strategies in specialist pathways.³

A clearly suspicious germ-cell tumour usually follows a more definitive oncological pathway.

What about tumour markers?

Blood tests such as alpha-fetoprotein (AFP), beta-human chorionic gonadotrophin (β-hCG) and lactate dehydrogenase (LDH) may be measured when testicular cancer is suspected.

Normal tumour markers do not rule out testicular cancer. They are used together with examination and ultrasound.

Should men regularly self-examine?

The practical goal is familiarity rather than constant anxious checking.

Knowing what your testes normally feel like makes a genuine new change easier to recognise. The epididymis behind the testicle can itself feel like a soft ridge or lump, which is one reason self-diagnosis can be misleading.

If you notice a new persistent lump, hard area, enlargement or change in consistency, arrange an examination rather than repeatedly trying to decide what it is yourself.

When does this need an urgent referral?

NICE recommends considering an urgent suspected-cancer referral for a non-painful enlargement or change in shape or texture of the testis, and direct-access scrotal ultrasound where the examination raises the question but does not settle it.

In practice the ultrasound is the step that resolves most of these, and it is quick. Privately it can usually be done on the same visit as the examination, which converts a fortnight of worry into an afternoon.

When is testicular pain an emergency?

Sudden severe testicular pain is a different problem from a chronic lump.

Testicular torsion occurs when the spermatic cord twists and cuts off blood supply. It requires urgent surgery.

A clinical review reports that the chance of saving the testicle is around 90% when treated within roughly six hours of symptom onset.¹

Seek emergency care for sudden severe unilateral testicular pain, especially if it is associated with nausea, vomiting or a high-riding testis.

Do not wait for a routine ultrasound appointment if torsion is suspected.

How strong is the evidence?

The UK primary-care cancer study is large and directly relevant to symptom presentation, although it is observational.²

The European radiology review provides useful evidence on incidental small lesions but applies to a different population from men with palpable masses.³

The general scrotal-mass review provides clinically useful synthesis, including emergency management, but is not a population prevalence study.¹

Bottom line

Most scrotal lumps are not automatically cancer, but a new testicular lump deserves proper assessment because examination alone cannot always determine its cause.

Ultrasound is the key test when the diagnosis is uncertain or a testicular lesion is suspected.^{1, 3}

The reassuring message is not “ignore it because most lumps are benign.” It is “most lumps have an explanation, and the safest route to reassurance is to establish what the lump actually is.”

And remember: sudden severe testicular pain is an emergency, not a routine lump assessment.

Please do not spend a fortnight examining yourself every evening trying to decide what a lump is. You cannot settle it that way and neither can I by touch alone — but an ultrasound usually settles it in minutes, and it can generally be arranged for the same visit as the examination. Most of the men I scan for this go home reassured. That is precisely why it is worth doing rather than worrying.