When a Hydrocele Is More Than a Hydrocele: Understanding Testicular Mesothelioma

Most people have never heard of mesothelioma of the tunica vaginalis, a rare form of mesothelioma that affects the lining of the testis, and that is sometimes referred to as mesothelioma of the testis. Most healthcare providers may never encounter a case during their careers due to its rarity.

Yet this rare cancer deserves attention because it can easily be mistaken for a much more common and usually harmless condition called a hydrocele.

A recently published medical case report titled “When a hydrocele is more than a hydrocele” described how a young man initially believed to have a routine hydrocele, was later diagnosed with malignant mesothelioma of the tunica vaginalis (testis), abbreviated as MMTVT.

Understanding this disease can help patients recognize when symptoms may warrant closer evaluation.

Important Note from our Nurse Regarding Family Planning

Mary Hesdorffer, RN, an expert with over 30 years treating mesothelioma says:

“Diseases associated with reproductive organs in men create a sense of fear and sadness with the thought of never having a child of their own. Preserving sexual function should be a priority as you would hope to resume a healthy and satisfying sexual life post treatment.  Sperm banking is a priority for some, and when feasible, a few of my patients were able to start a family after successful treatment. Consult with your medical team as to feasibility and timing as well as family counseling to help you both through this difficult time.”

What is Mesothelioma of the Tunica Vaginalis?

The tunica vaginalis is a thin membrane, comprised of mesothelial cells, that surrounds the testicle. It helps reduce friction and allows the testicle to move freely within the scrotum.

Mesothelioma develops in mesothelial cells, which form protective linings around certain organs such as the lungs and the abdomen. Most people, in fact, have heard of mesothelioma as mostly a cancer of the lining of the lungs, called pleural mesothelioma and don’t think about it as a possibility in other anatomic locations. However, mesothelioma can also arise in other areas, including:

• The abdomen
• The heart lining
• The lining of the tunica vaginalis which surrounding the testicles

Mesothelioma of the tunica vaginalis is extremely rare. According to research discussed in the paper and data from the National Institutes of Health (NIH), it accounts for less than 1% of all mesothelioma cases.

What Is a Hydrocele?

A hydrocele is a buildup of fluid around a testicle. It often causes swelling of the scrotum. Unlike mesothelioma, a hydrocele is usually benign.

Hydroceles are common and can develop from:

• Injury
• Infection
• Inflammation
• Prior surgery
• Unknown causes

Many hydroceles cause little pain and are not dangerous. Because hydroceles are so common, doctors may initially assume scrotal swelling is harmless.

The challenge is that mesothelioma of the tunica vaginalis often presents in exactly the same way.

Mistaking Mesothelioma for a Harmless Condition

One of the most important points in the case report is that MMTVT has no “pathognomonic” signs, meaning there is no single symptom or test finding that immediately identifies it.

Patients often experience:

• Scrotal swelling
• A hydrocele
• Mild pain or discomfort
• A feeling of heaviness

Some patients may also have:

• Thickened scrotal tissue
• Nodules
• Rapid enlargement of the scrotum
• A mass near the testicle

Because these symptoms overlap with far more common conditions, diagnosis is frequently delayed until surgery or pathology testing. A delayed diagnosis unfortunately also delays treatment and allows the mesothelioma cancer time to proliferate.

The paper describes a 37-year-old man who sought care for severe testicular pain and swelling. Ultrasound imaging showed a large hydrocele, but no obvious cancer. He was initially treated for epididymitis, an inflammation or infection near the testicle.

When the swelling did not improve, surgeons performed a hydrocelectomy to remove the hydrocele. Only afterward did pathology reveal malignant mesothelioma.

The Role of Asbestos Exposure

Just like in other mesotheliomas, asbestos exposure also plays a crucial role in the development of the mesothelioma of the tunica vaginalis.

The paper notes that approximately 30% to 40% of reported MMTVT cases involve known prior asbestos exposure.

However, not every patient has a known exposure history. Some patients diagnosed with this disease are relatively young and have no identifiable asbestos contact.

Possible asbestos exposure sources include:

• Navy service
• Shipyards
• Construction work
• Industrial settings
• Insulation materials
• Automotive brake work
• Talc exposure from use of baby powder
• Environmental talc exposure
• Second-hand exposure

In the featured case, the patient may have encountered asbestos while serving aboard an older Navy ship in the Middle East. However, at 37-years-old, it is also possible that he may have had earlier exposures possibly from a close family member who worked around asbestos (we don’t know his parents’ occupations), or from talc in baby powder.

NIH researchers and other investigators have also documented that asbestos-related diseases may appear decades after exposure. This long latency period can make it difficult for patients to connect their symptoms to past occupational environments.

Treatment for tunica vaginalis mesothelioma

The distinction between a simple hydrocele and mesothelioma is critical because the surgical approaches are very different.

A standard hydrocelectomy involves operating directly through the scrotum. According to the article, when mesothelioma is unknowingly treated this way, cancer cells may spread into nearby tissues or lymph nodes.

Researchers warn that this approach can increase the risk of recurrence by allowing for tumor seeding.

For suspected MMTVT, specialists instead recommend a more aggressive cancer surgery, typically involving:

• Radical inguinal orchiectomy
• Removal of affected tissue
• Possible hemiscrotectomy
• Evaluation of lymph nodes

The case report explains that the patient later underwent additional surgery after the diagnosis was confirmed. Fortunately, follow-up imaging showed no recurrence for longer than three years afterward.

Symptoms That May Deserve Closer Attention

The authors outlined several warning signs that may suggest a hydrocele is “more than a hydrocele.”

Potential red flags include:

• Rapid swelling over weeks or months
• Painful hydrocele
• Thickened or hard scrotal tissue
• Nodules or irregular texture
• Recurrent hydrocele
• Persistent swelling despite treatment
• A palpable mass

Ultrasound findings that may raise concern include:

• Thickened tunica vaginalis
• Nodular tissue
• Internal debris
• Increased blood flow on Doppler imaging

Still, even advanced imaging can miss the disease.

How Is It Diagnosed?

Definitive diagnosis usually requires pathology testing after tissue removal.

Pathologists examine the tissue under a microscope and may perform immunohistochemical staining to identify mesothelioma markers. In the featured case, the tumor tested positive for calretinin and WT-1, findings consistent with mesothelial cancer cells.

Doctors may also use:

• CT scans
• PET scans
• Bone scans
• Ultrasound
• Lymph node evaluation

Because the disease is so uncommon, there are currently no universally accepted surveillance guidelines specifically for MMTVT.

Prognosis and Follow-Up

Mesothelioma of the tunica vaginalis can behave aggressively.

The article cites studies reporting average survival ranging roughly from 18 to 36 months after diagnosis in some patient groups.

However, outcomes vary significantly depending on:

• Stage at diagnosis
• Whether cancer has spread
• Surgical completeness
• Patient age
• Tumor type

Patients with localized disease treated early may do substantially better.

Long-term monitoring is important because recurrences can occur years later. Experts often recommend:

• Regular physical exams
• Repeat ultrasounds
• CT imaging every few months initially
• Continued surveillance for up to 10 years

A Rare Disease with Important Lessons

This condition remains rare, and its rarity is part of the problem. Many patients and even physicians may not initially suspect cancer when evaluating a hydrocele.

The main lesson from the report is not that every hydrocele represents cancer. Most do not. Rather, the message is that persistent, painful, rapidly developing, or unusual hydroceles may deserve a more careful evaluation.

For patients with a history of asbestos exposure, especially veterans and industrial workers, awareness may be particularly important.

As researchers from NIH and other institutions continue studying mesothelioma of the tunica vaginalis, the hope is that earlier recognition and appropriate surgical management can improve outcomes for future patients.

If you need help with your case, contact Mary Hesdorffer, RN, a mesothelioma expert and author with 30 years of experience treating mesothelioma.