Testicular mesothelioma, a rare form of the disease, affects the tunica vaginalis in the testes and accounts for less than 5% of all cases. There are no unique symptoms, which can make diagnosis difficult. The best treatment option for mesothelioma patients with early-stage cancer is surgery.
Testicular Mesothelioma Symptoms
Signs of malignant mesothelioma of the tunica vaginalis are similar to other disorders of the testes. The most common symptoms include:
- Hydrocele (excess fluid and swelling in the scrotum)
- Testicular pain, swelling or discoloration
- Inflammation of the epididymis, a tube that carries sperm in the rear of the testicle
- A lump or mass under the skin that may be painless
- Spermatocele (cyst in the epididymis)
Malignant mesothelioma of the tunica vaginalis does not have a unique set of symptoms and presents similarly to more common testicular diseases. Doctors often diagnose the disease incidentally after an examination or surgery for another indication. Some patients are asymptomatic and display no signs at all.
A 2019 study of 113 patients found that 56% developed hydrocele and 33% had a lump or mass on the testes. In the majority of reported cases, early symptoms are not noticeable enough for patients to seek medical care. Without an early mesothelioma diagnosis, however, treatment options are limited to chemotherapy or radiation.
How Does Mesothelioma Cancer Develop in the Testes?
Testicular mesothelioma forms on the membrane that lines the testes called the tunica vaginalis. It’s a rare variant of mesothelioma that occurs in less than 5% of cases. Researchers are still working to understand how asbestos fibers cause mesothelioma to form in the testes.
Testicular mesothelioma develops as hard yellowish lesions on the surface of the tunica vaginalis. As they grow, the nodules cause thickening of the membrane and can damage the structures within the scrotum.
Causes of Testicular Mesothelioma
Asbestos exposure is a significant trigger for developing testicular mesothelioma. Other potential risk factors include:
- History of previous trauma to the groin
- Untreated or long-term hydrocele
- History of inguinal hernias
- Previous hernia repair surgery
- Age above 55 years
Prognosis for Testicular Mesothelioma
The prognosis for malignant mesothelioma of the tunica vaginalis is substantially more favorable than other types. Almost half of the patients with testicular mesothelioma survive for five or more years after diagnosis, while 33% survive at least 10 years.
Median life expectancy for mesothelioma of the tunica vaginalis is about 24 months. However, with limited data and a low number of total cases, survival rate values vary widely by disease stage and cell type.
Mesothelioma of the tunica vaginalis is an aggressive form of cancer, and 52% of patients develop local recurrence or metastasis.
The majority of patients have a diagnosis of epithelial cell type, which has a more favorable mesothelioma prognosis and a better response to treatment than other variants.
Diagnosing Testicular Mesothelioma
Due to the similarity of symptoms with other types of testicular disease, diagnosing mesothelioma of the tunica vaginalis can be difficult. This rare form of cancer can be mistaken for more common conditions such as an inguinal hernia or testicular adenocarcinoma.
If the treating physician suspects their patient has this rare form of mesothelioma, they will order imaging, such as an ultrasound, to investigate irregularities. An ultrasound, or Doppler, can show if there are lumps or masses in the testes as well as any areas of restricted blood flow.
Most cases only affect one testicle, but a bilateral presentation is possible. If the doctor notices abnormalities on the ultrasound they will perform a biopsy to confirm the diagnosis.
A biopsy involves removing a sample of tissue from the tumor within the testes and analyzing the cellular structure in the lab. Immunohistochemical staining informs the doctor of cancer and cell type, allowing them to develop a treatment plan.
Staging Testicular Mesothelioma
Due to the limited number of observed cases, there is no formal mesothelioma staging system for the testicular variant of the disease. However, determining how far the disease has progressed is an essential step in developing a treatment plan.
Early-stage disease indicates that cancer is localized and tumors have not formed outside of the testes. In the early stages, patients are more likely to have the option of surgical resection, which provides the best chance at prolonged survival.
Late-stage, advanced or end-stage imply that the disease has traveled to lymph nodes and organs outside the testes.
Testicular mesothelioma is aggressive and can spread quickly, limiting treatment options and worsening the prognosis. The most common sites of metastasis are the lungs in about 10% of patients and the liver in roughly 4% of patients.
Treating Testicular Mesothelioma
Doctors recommend surgery as a first-line treatment for testicular mesothelioma. Surgical resection involves removing the affected testicle and spermatic cord in a procedure called an orchiectomy.
In most of the reported cases, mesothelioma of the tunica vaginalis is localized to one testicle, simplifying the procedure. If cancer has spread to nearby lymph nodes, doctors will perform a lymphadenectomy to remove them.
Surgery is commonly followed by chemotherapy with cisplatin and pemetrexed, the conventional chemotherapy mesothelioma treatment. Chemotherapy infusion is useful for killing cancer cells that remain after surgery. Doctors may also prescribe radiation therapy as part of a multimodal treatment plan to prevent cancer from returning.
Because the number of total cases remains low, experts have not yet developed a standardized treatment plan for testicular mesothelioma. Some peritoneal mesothelioma patients may also develop tumors within the testicles, necessitating the treatment of both cancer sites.
Coping with Testicular Mesothelioma
Many men struggle with the emotional ramifications of testicular mesothelioma. Changes to the body can impact self-image and lead to feelings of depression. Many support groups exist to help patients cope with the emotional challenges of this rare disease.
Conversations about sexual and reproductive health can be difficult, especially after surgery, chemotherapy or radiation treatment.
Professional counselors, support from family and friends, and the American Cancer Society’s Life After Cancer guide can help patients find the next steps after cancer treatment. Talking to your doctor, your partner and your support network will reveal resources that will help you on the path to recovery.