Types of Mesothelioma

Primary Types of Mesothelioma

There are four main types of mesothelioma: Pleural, peritoneal, pericardial and testicular. Doctors name these types based on where the tumor first appears. Understanding these types can help us better discuss treatment options and support strategies.

Types of Mesothelioma 

• Pleural Mesothelioma: This is the most common type of mesothelioma, accounting for about 75% of all cases. It affects the lining of the lungs (pleura).
• Peritoneal Mesothelioma: The second most common type of mesothelioma forms in the lining of the abdomen (peritoneum). According to SEER data, it accounts for 10% to 30% of cases.
• Pericardial Mesothelioma: A rare mesothelioma type that develops in the lining of the heart (pericardium), accounting for 1% of all mesothelioma cases.
• Testicular Mesothelioma: Testicular mesothelioma is the most rare type with tumors forming on the lining of the testes (tunica vaginalis). It accounts for less than 1% of cases.

Mesothelioma comes in four types, and they all develop in the mesothelium, which is the thin layer of tissue lining various organs and body cavities. This lining is made up of mesothelial cells. Unfortunately, these cells can become cancerous after exposure to asbestos.

Epithelioid cells are the most common type of cell found in mesothelioma tumors. Noncancerous or benign mesothelioma tumors are rare.

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Pleural Mesothelioma

Surgery is an important option for treating early-stage pleural mesothelioma. Patients who undergo stage 1 treatment often enjoy longer lives—around 3 years or more—compared to about 12 months with stage 4 treatment. It’s also encouraging to note that there are many clinical trials focused on pleural mesothelioma, giving patients more opportunities for innovative treatments.

Peritoneal Mesothelioma

Many patients with peritoneal mesothelioma have a good chance of benefiting from surgery combined with heated chemotherapy. About 50% of these patients can qualify for this treatment, which can help them live five years or more after their diagnosis. While the outlook for peritoneal mesothelioma is generally more positive than for pleural mesothelioma, there is still a need for more research in this area.

Pericardial Mesothelioma

For treatment, options may include surgery, chemotherapy and radiation. A 2022 case published in the Journal of Thoracic Oncology found that patients treated with a combination of these methods had a median survival time of 25.9 months, while those receiving trimodal treatment could live for a median of 70 months. It’s important to discuss all available treatment options with a health care provider to find the best plan.

Testicular Mesothelioma

Common symptoms can include scrotal swelling and lumps that may not cause pain. If diagnosed, several treatment options are available, such as surgery and chemotherapy. Additionally, patients might have the chance to participate in clinical trials, which can offer new possibilities for care. With these treatments, many patients can enjoy an average of over two years of life after their diagnosis, which is a hopeful outcome.

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Three Primary Mesothelioma Cell Types

There are three main types of mesothelioma cells: Epithelioid, sarcomatoid and biphasic. Biphasic is a combination of the first two types.

Asbestos exposure can lead to malignant mesothelioma cancer, and how tumors respond to treatment can differ. Generally, epithelioid cells respond the best to treatment, while sarcomatoid cells tend to be more resistant.

Doctors who specialize in cancer consider these differences when creating your treatment plan. They tailor the plan to fit the specific type of mesothelioma you have. The occurrence of these cell types can also vary depending on where the cancer is in the body.

For example, pericardial mesothelioma shows a roughly equal distribution of the three main cell types, with biphasic being the least common. In most cases of testicular mesothelioma, only epithelial cells are present, and there has only been one reported case of sarcomatoid cells in this type.

Rare Mesothelioma Cell Subtypes

There are three main types of mesothelioma cells, and each can be divided into subtypes such as benign and paillary. These subtypes have their own special characteristics that can be seen under a microscope.

Benign mesothelioma is part of the epithelial category and usually responds well to treatment. However, some rare subtypes, such as desmoplastic, can be trickier to diagnose and treat. Learning about these subtypes is important for planning effective management and treatment.

Benign Mesothelioma

Benign mesothelioma is a rare type of noncancerous tumor that appears in the lining of the lungs or abdomen. These tumors grow more slowly and typically form one large mass instead of many small ones, which is good news since they don’t spread to other parts of the body.

There are different subtypes of benign mesothelioma, such as benign multicystic, adenomatoid, localized fibrous, and papillary. It’s interesting to note that adenomatoid cells can be found in both benign and malignant mesothelioma cases.

Papillary Mesothelioma

Well-differentiated papillary cells are mainly found in peritoneal mesothelioma. However, some cases have also appeared in other areas, like a 2024 case in the pleura. To reduce confusion with the malignant form, researchers renamed this condition “well-differentiated papillary tumor” in 2022, dropping the term “mesothelioma.”

This subtype is usually viewed as benign, but there have been instances where it became malignant. The common treatment involves surgery and heated chemotherapy to manage the condition. If the tumors return, doctors will often repeat these procedures to help keep them under control.

Other Rare Mesothelioma Cell Subtypes

Rare cell types can be tricky to diagnose because they are not very common. They have small differences that can be hard to spot. Understanding these differences is important, as they can influence a person’s prognosis and life expectancy.

Rare Cell Subtypes 

• Cystic
• Deciduoid
• Desmoplastic
• Heterologous
• Localized fibrous
• Lymphohistiocytoid
• Small cell

Certain subtypes are associated with pleural or peritoneal mesothelioma. Treatment for rare subtypes depends on the primary cell type.

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Treatment by Type of Mesothelioma

Your mesothelioma diagnosis plays an important role in shaping your treatment plan and the options available to you. Doctors will look at the type of tumor and cells involved. They will also take into account your age and overall health, along with your personal wishes and needs as you start treatment.

A well-rounded mesothelioma treatment plan often includes different approaches. For younger patients in good health, surgery can be a great option. Additionally, chemotherapy, radiation, and immunotherapy are available and can benefit many patients.

Chemotherapy 

Standard chemotherapy for mesothelioma typically uses two main drugs. For the pleural type, doctors often recommend a combination of cisplatin and pemetrexed (Alimta). For the peritoneal variant, drugs like gemcitabine and carboplatin may work better.

In a 2023 survey by The Mesothelioma Center, participants who reported remission were 32% more likely to have received cisplatin than those who didn’t.

Unfortunately, there isn’t a specific chemotherapy plan for the rare pericardial or testicular forms of mesothelioma. Because these types are uncommon, a specialist can help create a personalized treatment plan that considers your treatment history, cancer type, and overall health.

Immunotherapy

In 2020, the FDA approved the use of immunotherapy medications nivolumab (Opdivo) and ipilimumab (Yervoy) together as a primary treatment for pleural mesothelioma. This combination has shown promising results, with a median overall survival of about 18 months, which is an improvement over the 12-14 months typically seen with standard chemotherapy.

While many pleural mesothelioma patients benefit from immunotherapy, the results for those with peritoneal mesothelioma are not as clear. The rarity of peritoneal mesothelioma means there is limited clinical trial data available. However, some studies suggest that immunotherapy may help certain peritoneal patients. Research is ongoing, and some patients are able to access this treatment through clinical trials.

Surgery

Surgery options for mesothelioma can differ quite a bit, as they focus on different areas of the body. Generally, surgery is a good choice for younger patients who are in good health and have been diagnosed with an earlier stage of cancer.

Mesothelioma Surgeries

• Pleural Mesothelioma Surgery: One option is an extrapleural pneumonectomy, which removes the cancerous lung and surrounding structures. Another is a pleurectomy, which takes out the pleural lining of the lungs. Decortication helps remove tumors from the chest area.
• Peritoneal Mesothelioma Surgery: A peritonectomy is designed to remove tumors from the abdominal lining and parts of organs like the stomach, intestines, liver, pancreas, and spleen.
• Pericardial Mesothelioma Surgery: For pericardial mesothelioma, a pericardiectomy can be performed to remove the outer sac around the heart.
• Testicular Mesothelioma Surgery: In cases involving testicular mesothelioma, surgeons typically perform an inguinal orchiectomy.

Recovery after surgery can vary based on how complex the operation is and if any additional treatments, like heated chemotherapy, are included. Your treatment team will talk with you in advance about what to expect during recovery, so your family can be well-prepared at home.

Radiation Therapy

Doctors often use radiation together with surgery to help slow down tumor growth in pleural mesothelioma. When used by itself, radiation can shrink tumors and ease symptoms, which is a positive outcome for many patients.

While radiation therapy is not commonly used for patients with peritoneal mesothelioma, it’s important to know that it may affect some organs, like the kidneys or liver. However, for those with pericardial or testicular mesothelioma, radiation can be quite helpful.

Palliative Treatment

Palliative therapy aims to help manage pain and other symptoms related to cancer. It can be a valuable part of a broader treatment plan, and it often enhances your quality of life and overall well-being.

For instance, one helpful palliative treatment for mesothelioma is thoracentesis. This procedure removes excess fluid around your lungs, relieving discomfort. Similarly, paracentesis helps by draining fluid from your abdomen. Both procedures can make breathing and eating more comfortable, making you feel better in your daily life.

Common Questions About the Types of Mesothelioma

What is the difference between mesothelioma cell types and tumor location?

Cell type refers to the type of cells that make up the tumors. Tumor location refers to where the cancer first began growing, such as the lining of the lungs or abdomen.

How does the type of mesothelioma impact prognosis and treatment?

The type of mesothelioma a patient has impacts their overall prognosis and recommended treatments. Mesothelioma treatment is complex, and many other factors influence treatment options and prognosis, such as the stage of the cancer.

How can I find a mesothelioma specialist for my type of mesothelioma?

You can speak with a Patient Advocate to find a mesothelioma specialist who has experience treating your type of mesothelioma.

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