Primary Types of Mesothelioma
The 4 main types of mesotheliomas are pleural, peritoneal, pericardial and testicular. The names of these types are based on where they initially develop in your body.
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).
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Peritoneal mesothelioma: The second most common type of mesothelioma forms in the lining of the abdomen (peritoneum).
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Pericardial mesothelioma: A rare mesothelioma type that develops in the lining of the heart (pericardium).
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Testicular mesothelioma: The most rare type with tumors forming on the lining of the testes (tunica vaginalis).
All 4 types of mesothelioma form in the tissue called the mesothelium that lines different organs and body cavities. This lining is made up of mesothelial cells that can turn cancerous following asbestos exposure.
Epithelioid cells are the most common type of cell found in mesothelioma tumors. Noncancerous or benign mesothelioma tumors are rare.
Pleural Mesothelioma
Aggressive surgery provides the best outcome for early-stage pleural mesothelioma. Patients can live for 3 or more years with stage 1 treatment versus roughly 12 months with stage 4 treatment. There are more clinical trial studies on pleural mesothelioma than any other type.
Peritoneal Mesothelioma
About 50% of all peritoneal mesothelioma patients are eligible for surgery with heated chemotherapy, which helps many patients live 5 or more years after diagnosis. The prognosis for peritoneal mesothelioma is better than for the pleural type, but there is less available research.
Pericardial Mesothelioma
Treatment may include surgery, chemotherapy and radiation. A 2022 case series reported a median overall survival of 25.9 months, and trimodal treatment patients surviving a median of 70 months.
Testicular Mesothelioma
Symptoms include scrotal swelling and painless testicular lumps. Treatment options include surgery and chemotherapy, and clinical trials may be available as well. These therapies can help patients live more than 2 years, on average, after diagnosis.
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Three Primary Mesothelioma Cell Types
Epithelioid, sarcomatoid and biphasic are the 3 main types of mesothelioma cells. Biphasic is a mix of the first 2 mesothelioma cell types.
Asbestos exposure causes the malignant form of mesothelioma cancer. Tumors vary in response to treatment. Epithelial or epithelioid cells respond the best. Sarcomatoid cells are more resistant to treatment.
Cancer doctors take these differences into account, creating your treatment plan around your specific type of mesothelioma. The incidence and frequency of these cell types vary by cancer location.
Pericardial mesothelioma exhibits a roughly equal distribution of the 3 primary cancer cell types. The minority are biphasic. Most testicular cases contain only epithelial cells. There is only a single case of sarcomatoid cell disease for this type.
Rare Mesothelioma Cell Subtypes
The primary 3 mesothelioma cell types can be further classified into subtypes, each with distinct traits visible under a microscope. These subtypes have unique features that set them apart from the classic definitions of the primary types.
While benign mesothelioma falls into the epithelial category and typically responds better to treatment, other rare subtypes often present greater challenges in diagnosis and treatment. Understanding these subtypes is crucial for effective management and treatment planning.
Benign Mesothelioma
Benign mesothelioma is a rare noncancerous tumor in the lining of the lungs or abdomen. These cells don’t spread to other parts of the body and grow more slowly, often forming one large mass instead of many small ones.
Examples of benign cell subtypes include benign multicystic, adenomatoid, localized fibrous, papillary and mesothelioma of uncertain malignant potential. Adenomatoid cells can occur in both malignant mesothelioma and benign mesothelioma.
Papillary Mesothelioma
Well-differentiated papillary cells primarily occur in cases of peritoneal mesothelioma. The literature documents some cases in other locations, including a 2024 case found in the pleura. Researchers dropped ”mesothelioma” from this condition’s name in 2022 and renamed it “well-differentiated papillary tumor” to limit confusion with the malignant disease.
This subtype is generally considered benign, but some cases have turned malignant. Treatment generally involves surgery and heated chemotherapy. In cases that return, doctors repeat these procedures to keep tumors under control.
Other Rare Mesothelioma Cell Subtypes
Rare cell types are irregular and are more challenging to diagnose. They have subtle differences among them. They may also affect prognosis and life expectancy.
Rare Cell Subtypes
- Cystic
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Deciduoid
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Desmoplastic
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Heterologous
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Localized fibrous
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Lymphohistiocytoid
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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 specific mesothelioma diagnosis will influence your treatment plan and various treatment options. These depend on tumor and cell type. Doctors must also consider your age and general health, as well as assess your wishes and needs going into treatment.
A proper mesothelioma treatment plan is often multimodal, involving many therapies. Surgery is an appropriate option for patients who are younger and in good health. Chemotherapy, radiation and immunotherapy are available to a broader range of patients.
Chemotherapy
Standard chemotherapy for mesothelioma involves 2 drugs. The most common combination for the pleural form of mesothelioma is cisplatin and pemetrexed (Alimta). Gemcitabine, carboplatin and other drugs are more effective against the peritoneal variant.
The chemotherapy drug cisplatin was 32% more common among respondents of The Mesothelioma Center’s 2023 survey who reported having remission than those who didn’t.
No chemo drug is particularly effective for the pericardial or testicular forms. These types are so rare that there is no standard chemotherapy plan. A specialist can devise the best plan for you based on your treatment history, cancer type and health.
Immunotherapy
The FDA granted approval for the combined use of immunotherapy medications nivolumab (Opdivo) and ipilimumab (Yervoy) as a frontline treatment for pleural mesothelioma in 2020. This treatment has a median overall survival of approximately 18 months, surpassing the survival range of 12-14 months seen with traditional chemotherapy.
While immunotherapy is proven to work for many pleural patients, studies show mixed results for peritoneal patients. Because of the rarity of peritoneal mesothelioma, limited clinical trial data exists. Certain studies suggest that immunotherapy may offer benefits in select cases of peritoneal mesothelioma. Research continues in clinical trials, which is where some peritoneal patients access this treatment.
Survivor Story
My mesothelioma journey has been difficult at times, but I try to remain positive. I returned home from extrapleural pneumonectomy surgery a week or so after getting out of the ICU. I started chemotherapy about 3 months later with rounds of cisplatin and Alimta. After recurrence, I began targeted radiation therapy coupled with immunotherapy. My mesothelioma is currently under control.
Read Michael’s Story
Surgery
Surgeries for mesothelioma vary greatly because they involve operating on different parts of the body. Surgery is generally an option for patients who are younger, in good health and diagnosed with an earlier stage of cancer.
Mesothelioma Surgeries
- Pleural Mesothelioma Surgery: An extrapleural pneumonectomy removes the cancerous lung and nearby structures. A pleurectomy extracts the pleural lining of the lungs. Decortication removes tumors in the chest.
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Peritoneal Mesothelioma Surgery: A peritonectomy removes tumors from the abdominal lining and portions of various organs that may include the stomach, intestines, liver, pancreas and spleen.
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Pericardial Mesothelioma Surgery: A pericardiectomy removes the outer heart sac.
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Testicular Mesothelioma Surgery: For testicular patients, surgeons perform an inguinal orchiectomy.
Recovery from surgery depends on how intensive the operation is and whether it involves the delivery of other therapies, such as heated chemotherapy. Your treatment team will discuss the recovery process with you beforehand to make sure your family is prepared at home.
Radiation Therapy
Doctors use radiation alongside surgery to slow tumor growth in pleural mesothelioma. Used alone, it can shrink tumors and help relieve symptoms.
Radiation therapy isn’t typical for peritoneal patients. It may harm some organs, such as the kidneys or liver. Radiation can benefit pericardial and testicular patients.
Palliative Treatment
The goal of palliative therapy is to manage pain and other cancer symptoms. Palliative care may be part of a multimodal treatment plan, and it can improve your quality of life and well-being.
One example of a palliative treatment for mesothelioma is thoracentesis. This procedure drains fluid from around your lungs. Paracentesis removes fluid from your abdomen. These procedures can ease your pain and pressure and make breathing and eating easier.
Common Questions About the Types of Mesothelioma
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What is the difference between mesothelioma cell types and tumor location?
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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.
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How does the type of mesothelioma impact prognosis and treatment?
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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.
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How can I find a mesothelioma specialist for my type of mesothelioma?
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You can speak with a Patient Advocate to find a mesothelioma specialist who has experience treating your type of mesothelioma.
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