Epithelioid Mesothelioma

Malignant epithelioid mesothelioma develops when healthy epithelial cells become cancerous after a person is exposed to asbestos. This cell type usually originates in the pleura (lining of the lungs) and grows slowly. Epithelioid mesothelioma has the best prognosis of all cell types, but it requires prompt and aggressive treatment from a mesothelioma specialist.

What Is Epithelioid Mesothelioma?

Epithelioid mesothelioma is the most common mesothelioma cell type, accounting for 70% of all malignant mesothelioma cases. This cell type is more commonly observed in cases of pleural mesothelioma than peritoneal mesothelioma.

The terms “epithelioid mesothelioma” and “epithelial mesothelioma” are interchangeable.

How Epithelioid Mesothelioma Develops

Epithelial cells line the body’s organs and blood vessels, acting as a barrier and filter.

When asbestos particles are inhaled, the lungs attempt to remove them, and they end up lodged in mesothelial cells. After these cells encounter the asbestos, mutations can occur.

The mutated epithelial mesothelioma cancer cells multiply rapidly, forming dangerous tumors within the pleura.

Characteristics of Epithelioid Mesothelioma Cells

Notable features of healthy epithelial cells include:

  • Elongated
  • Rounded, oval, or egg-shaped
  • Visible nucleus
  • Uniformly arranged appearance

Although these visible features can make epithelioid mesothelioma easier to identify, this cell type often resembles other malignant cells typically found in the chest and abdomen.

For this reason, doctors must carefully study mesothelioma tumors to reach the right diagnosis.

How Do Epithelial Cells Behave?

  • Divide at the slowest rate compared to other mesothelioma cell types
  • Sometimes spread to nearby lymph nodes
  • Stick to each other as they spread
  • Less likely to spread to distant parts of the body (metastasize)

Their slower growth rate and lower likelihood of metastasis typically make epithelioid cells easier to manage with treatment than the other mesothelioma cell types (sarcomatoid and biphasic).

Epithelioid Mesothelioma Symptoms

Epithelioid mesothelioma symptoms vary by where in the body the cancer originates.

Symptoms of Pleural Epithelioid MesotheliomaSymptoms of Peritoneal Epithelioid Mesothelioma
Shortness of breathAbdominal pain and/or swelling
Chest painDigestive issues (constipation or diarrhea)
Pain in the ribs, shoulder, or upper backLoss of appetite
FeverPain in the abdomen
Fluid buildup in the lungs (pleural effusions)Night sweats
General fatigueVomiting and nausea

Epithelioid Mesothelioma Diagnosis

Pathologists diagnose epithelioid mesothelioma by performing a biopsy, which involves removing and examining a small amount of cancerous tissue or fluid. Doctors may also use lab tests, such as X-rays and CT scans, during the diagnostic process.

Doctors can tell the epithelioid cell type apart from other mesothelioma cell types by their shape under a microscope. Another way doctors can do this is by looking for unique properties through a process called immunohistochemical staining.

Immunohistochemistry and Diagnosis

Immunohistochemistry is a form of diagnostic testing that looks for the presence of certain proteins in a tissue sample that are unique to a disease.

To diagnose epithelioid mesothelioma, doctors need to eliminate other potential diseases. Immunohistochemistry can highlight proteins that are known to be present in epithelioid mesothelioma. It can also confirm the absence of proteins related to other diseases.

One of the primary immunohistochemical biomarkers for epithelioid mesothelioma is calretinin, which has been found in nearly all cases of this cancer type.

Epithelioid Mesothelioma Treatment

Patients diagnosed with malignant epithelioid mesothelioma have the most treatment plan options. They also respond more positively to treatment compared to those with other cell types.


Mesothelioma patients with epithelioid cells are more commonly diagnosed with the pleural form of this cancer.

Patients with pleural epithelioid mesothelioma may be eligible to undergo one of the following curative (life-extending) surgeries: extrapleural pneumonectomy (EPP) or pleurectomy with decortication (P/D).

EPP is most commonly performed on patients with localized epithelioid mesothelioma, in which the cancer hasn’t invaded the lymph nodes.

Mesothelioma surgery involves removing the tumor and surrounding tissue to slow the spread or return of the cancer. These procedures can increase the survival time of patients by years, especially when performed alongside other treatments (multimodal therapy).


Chemotherapy is a good option for most patients with epithelioid mesothelioma. Slow-growing epithelioid cells take longer to return after they are wiped out by chemotherapy drugs.

Currently, the most widely-used chemotherapy drug combination for mesothelioma is pemetrexed plus cisplatin.


Mesothelioma doctors typically use radiation alongside surgery and/or chemotherapy to kill cancer cells. Radiation therapy is not commonly used on its own to treat epithelioid mesothelioma because of its potential to cause damage to healthy tissue.

Other Treatment Options

Up-and-coming treatment options for epithelioid mesothelioma patients may be available through clinical trials. Emerging treatments like immunotherapy and targeted therapy are currently being studied and show the potential to be effective.

Case Study: Clinical Trial for Epithelioid Mesothelioma
A 2020 article in the journal Lung Cancer details an epithelioid mesothelioma patient whose cancer spread to her brain and other organs. After doctors administered immunotherapy to control the cancer’s spread, the patient has had no mesothelioma symptoms as of April 2020.

Seek Treatment From a Mesothelioma Specialist

Oncologists (cancer doctors) who specialize in mesothelioma are experts at diagnosing and treating this rare form of cancer. Seeking a second opinion from a specialist may help to avoid a misdiagnosis and improve mesothelioma prognosis.

“Epithelioid mesothelioma is the more favorable subtype of mesothelioma and carries a greater chance of survival after surgical and multimodality therapy.”

– Dr. Alexander Farivar, Mesothelioma Specialist

Our team of patient advocates can help connect you with a top mesothelioma doctor. Call us now at (866) 608-8933 for assistance.

Epithelioid Mesothelioma Prognosis

Mesothelioma has a generally poor prognosis (patient outlook). That said, patients with epithelioid mesothelioma have the best prognosis and survival rates of all cell types.

Because epithelioid mesothelioma cells stick together as they grow, they are more likely to stay in one area of the body. In turn, epithelioid mesothelioma is easier to treat than biphasic and sarcomatoid mesothelioma, which spread through the body quickly.

Overall, 73% of patients with epithelioid mesothelioma survive at least 1 year after diagnosis, and 12% survive 4 years.

Rare Types of Epithelioid Mesothelioma Cells

There are several rare types of epithelioid mesothelioma that may lead to differences in symptoms, life expectancy, and treatment options.

Learn about these epithelioid mesothelioma subtypes below.

Adenoid Cystic Mesothelioma

Adenoid cystic mesothelioma displays tubular patterns with inflammatory cells spaced throughout. This pattern has many small holes in between the cells.

Adenomatoid Mesothelioma

The pattern presented by adenomatoid mesothelioma consists of flat and cube-like cells that rest beside glandlike structures.

Clear-Cell Mesothelioma

Clear-cell mesothelioma has tumor cells with a cytoplasm that is clear, meaning the cell is relatively see-through.

Deciduoid Mesothelioma

Deciduoid mesothelioma is characterized by large cells with distinctive borders and shapes.

Glandular Mesothelioma

The pattern presented by glandular mesothelioma consists of flat or cuboidal cells that line small structures.

Papillary Mesothelioma

Papillary mesothelioma is characterized by a single layer of cuboidal cells with very low mitotic activity.

Small-Cell Mesothelioma

This form of mesothelioma is considered extremely rare. It consists of small, round cells with high rates of nuclei.

Solid Mesothelioma

Solid mesothelioma is a common histological pattern and is characterized by round cells that occur in nests, cords, or sheets.

Tubulopapillary Mesothelioma

The pattern associated with tubulopapillary mesothelioma is one of the most common and consists of small tubules and papillary structures that are lined by flat, uniform cells.

Frequently Asked Questions

What is the difference between epithelioid mesothelioma and pleural mesothelioma?

Epithelioid is a cell type, while pleural refers to the location/type of cancer. That said, a patient can have epithelioid malignant pleural mesothelioma, meaning the epithelioid cells within the lung lining are affected by the cancer.

How will a doctor be able to tell which form of mesothelioma I have?

Doctors will generally perform a biopsy to retrieve tissue from the area of concern. They will likely use immunohistochemical staining to determine which cell types are present and affected by the mesothelioma.

How long should I wait before consulting a physician if I think I have epithelioid mesothelioma?

If you believe you may have mesothelioma, it is important to talk to a doctor as soon as possible. A mesothelioma doctor has specialized experience with this type of cancer, allowing them to make an accurate diagnosis and informed treatment decisions.

Connect With a Mesothelioma Doctor

If you or a loved one believes they may have epithelioid mesothelioma, the Mesothelioma Hope Team can help you connect with a specialist.

We are here to help you get the best treatment and support — call us at (866) 608-8933 today.

Mesothelioma Support Team

Mesothelioma Hope was founded by a team of advocates to educate people about this aggressive form of cancer. Mesothelioma affects thousands of people each year. We help give hope to those impacted by mesothelioma.

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