Primary Types of Mesothelioma

The four primary types of mesothelioma are pleural, peritoneal, pericardial and testicular. The type of mesothelioma you’re diagnosed with is based on the location of the tumor within the body. Each mesothelioma type can lead to different symptoms. Mesothelioma cell type, the stage of the disease’s progression and a patient’s overall health are taken into account when determining a treatment plan.

There Are 4 Mesothelioma Types

  • Pleural Mesothelioma: Affects the lining of the lungs.
  • Peritoneal Mesothelioma: Affects the lining of the abdomen.
  • Pericardial Mesothelioma: Affects the lining of the heart.
  • Testicular Mesothelioma: Affects the lining of the testes.

Mesothelioma prognosis depends on tumor location, cell type and response to treatment. Epithelioid cells are the most common type of cell found in mesothelioma tumors. They are the most responsive to treatment. 

Pleural Mesothelioma diagram
Diagram showing where pleural mesothelioma forms.

Pleural Mesothelioma

Pleural is the most common mesothelioma type. About 70% to 75% of cases occur in the pleura, the outer lung tissue. Mesothelioma can also spread from the lungs to the abdominal cavity. There are more clinical trial studies on pleural mesothelioma than any other variant.

Aggressive surgery provides the best outcome for early-stage pleural mesothelioma. Unfortunately, doctors often diagnose patients after symptoms appear in later stages.

Typical pleural mesothelioma symptoms include:
  • Chest pain
  • Fatigue
  • Fever
  • Shortness of breath
  • Weight loss

Most patients qualify for chemotherapy or radiation therapy. Many are also eligible for clinical trials or immunotherapy. These therapies can add months or years to mesothelioma life expectancy. Patients can live for three or more years after stage 1 treatment versus roughly 12 months at stage 4.

Peritoneal Mesothelioma, the type of mesothelioma affecting the abdomen
Diagram showing where peritoneal mesothelioma forms.

Peritoneal Mesothelioma

Peritoneal mesothelioma begins in the lining of the abdomen and forms in the tissue that surrounds the abdominal organs. This variant accounts for 10% to 20% of all cases. The prognosis is better than the pleural type, but there is less available research.

Symptoms of peritoneal mesothelioma include:
  • Abdominal pain
  • Abdominal swelling
  • Bloating
  • Loss of appetite
  • Bowel changes

About half of all peritoneal mesothelioma patients are eligible for surgery with heated chemotherapy. This procedure, known as HIPEC, has helped patients live five or more years after diagnosis.

Pericardial Mesothelioma diagram
Diagram showing where pericardial mesothelioma forms.

Pericardial Mesothelioma

The pericardial mesothelioma tumor type is very uncommon. Only about 200 cases exist in medical literature records. It accounts for approximately 1% of all mesothelioma cases. With surgery, some patients live beyond the average six-month life expectancy.

Symptoms of pericardial mesothelioma include
  • Irregular heartbeat
  • Chest pain
  • Difficulty breathing
  • Cough

The pericardial form of mesothelioma develops in the protective heart sac known as the pericardium. Life expectancies of the cases on record range between six weeks and 15 months.

Testicular Mesothelioma, the type of mesothelioma affecting the testes
Diagram showing where testicular mesothelioma forms.

Testicular Mesothelioma

Testicular mesothelioma develops in the outer lining of the testes. Tumors form on tissue called the tunica vaginalis. This form of mesothelioma is the rarest. Fewer than 100 cases exist in medical literature, which is less than 1% of all mesothelioma cases.

Symptoms include scrotal swelling and painless testicular lumps. Treatment options include surgery and chemotherapy. These therapies can help people live more than two years, on average, after diagnosis.

Three Primary Mesothelioma Cell Types

The three mesothelioma cell types are epithelial, sarcomatoid and biphasic. Biphasic is a mix of the first two cancer 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 when planning treatment around a specific type of mesothelioma. The incidence and frequency of these cell types vary by cancer location.

Prevalence of Mesothelioma Tumors and Cell Types

Cell Type Pleural Tumors Peritoneal Tumors
Epithelioid 50% 75%
Sarcomatoid 20% 4%
Biphasic 30% 24%

Pericardial mesothelioma exhibits a roughly equal distribution of the three primary cancer cell types. The minority are biphasic. Most testicular cases contain only epithelial cells. There is only one case of sarcomatoid cell disease for this type.

Epithelial cells
A pathology stain showing epithelial mesothelioma cells under a microscope.

Epithelial Cell Subtype

Epithelioid mesothelioma occurs in 70% to 75% of cases. Patients with epithelioid cell tumors have the best prognosis.

This subtype tends to be less aggressive and doesn’t spread as fast as other cell types.

About 50% of pleural disease is epithelioid. Around 75% of peritoneal tumors are epithelioid.

Sarcomatoid Cell Subtype

Sarcomatoid mesothelioma is the least common mesothelioma cell type. It accounts for around 10% to 20% of all mesothelioma diagnoses. This cell type is the most aggressive and challenging to treat.

Sarcomatous, spindle or diffuse malignant fibrous mesothelioma refer to the same variant. About 20% of pleural tumors are sarcomatoid. Only about 1% of peritoneal cases are sarcomatous.

Biphasic mesothelioma cells
A pathology stain showing biphasic mesothelioma cells under a microscope.

Biphasic Cell Subtype

Biphasic mesothelioma refers to tumors that contain epithelial and sarcomatoid cells. Life expectancy for this variant depends upon which of the two appears most.

More epithelioid cells generally mean a better prognosis. If the tumor is high in sarcomatoid cells it is harder to treat and life expectancy is shorter. Around 30% of pleural and 25% of peritoneal tumors are biphasic.

Sarcomatoid, mixed (biphasic) and epithelial express themselves within the patient in a different manner. It’s important to understand which of these three types the physician is dealing with in a patient.
Dr. Sugarbaker

Mesothelioma Cell Subtypes

The primary three mesothelioma cell types may be further classified into subtypes. The subtypes of benign cells fall into the epithelial category. Benign mesothelioma is rare, and it tends to respond better to treatment. Other rare subtypes respond more poorly to treatment.

Benign Mesothelioma

Benign mesothelioma is a noncancerous tumor in the lining of the lungs or abdomen. The mesothelioma cell types found in benign tumors behave differently from cancerous tumors. Unlike cancerous cells, benign cells don’t spread into other parts of the body. These tumors also grow more slowly. Instead of lots of small masses, they often make one big mass.

Examples of benign cell subtypes include benign multicystic, adenomatoid, localized fibrous and papillary cells. Adenomatoid cells can occur in both malignant mesothelioma and benign mesothelioma.

Papillary Mesothelioma

Well-differentiated papillary cells primarily occur in cases of peritoneal mesothelioma. Some cases have been documented in other locations. This subtype is generally considered benign, but some rare cases has turned malignant.

Treatment generally involves surgery and heated chemotherapy. In cases that return, these procedures are repeated 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 include:
  • Adenomatoid
  • Benign multicystic
  • Cystic
  • Deciduoid
  • Desmoplastic
  • Heterologous
  • Localized fibrous
  • Lymphohistiocytoid
  • Papillary
  • Small cell

Patients with sarcomatoid tumors tend to have shorter life expectancies. Yet, some patients with the lymphohistiocytoid subtype have survived six years or more.

Certain subtypes are associated with pleural or peritoneal mesothelioma. For example, desmoplastic and lymphohistiocytoid are more common in pleural mesothelioma. A little more than half of the cases of deciduoid mesothelioma occur in the abdomen. Slightly less than half arise in the lung lining. Cystic and papillary cells are more common in peritoneal mesothelioma. Small cell mesothelioma is another cell type that occurs more commonly in the abdomen.

Treatment for rare subtypes depends on the primary cell type. For example, lymphohistiocytoid cells respond well to immunotherapy because it also works well on sarcomatoid cells.

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. A mesothelioma doctor or other health care professional is likely to prescribe a range of tests for diagnosis. These might encompass: blood examinations, lung capacity assessments and imaging tests such as chest X-rays, CT scans, PET scans and occasionally MRI scans.

Doctors must also consider the patient’s age and general health. The provider will also assess the patient’s desires 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.


There are two recommended surgeries for pleural mesothelioma.

  • Extrapleural Pneumonectomy: This procedure removes the cancerous lung and nearby structures.
  • Pleurectomy and Decortication: A pleurectomy extracts the pleural lining of the lungs. The decortication removes tumors in the chest.

Surgeries also exist for other variants. A peritonectomy removes the abdominal lining. A pericardiectomy removes the outer heart sac. For testicular patients, surgeons perform an inguinal orchiectomy.

Chemotherapy Drugs

Standard chemotherapy involves two drugs. The most common combination for the pleural form of mesothelioma is cisplatin and Alimta (pemetrexed). Gemcitabine, carboplatin and other drugs are more effective against the peritoneal variant.

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 chemotherapy plan. They base this decision on treatment history, cancer type and patient health.

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 reduce pain and other cancer symptoms. Palliative care can improve a patient’s quality of life and well-being.

One example is thoracentesis. This procedure drains fluid from around the lungs. Paracentesis removes fluid from the abdomen. These procedures can ease pain and pressure and make breathing and eating easier.

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Common Questions About the Types of Mesothelioma

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

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

How does the type of mesothelioma impact prognosis and treatment?

The type of mesothelioma a patient has impacts which treatments will be recommended and their overall prognosis. 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.