Written By: Devin Golden

Malignant Epithelioid Mesothelioma

Epithelioid mesothelioma cancer is the most common mesothelioma cell type, accounting for more than half of cases. Patients with this diagnosis typically have the most promising prognosis, as this cell type is the most treatable.

Karen Ritter, RN BSN

Medically Reviewed By

Karen Ritter, RN BSN

Registered Nurse

Karen Ritter, RN BSN

Medically Reviewed By

Karen Ritter, RN BSN

Registered Nurse


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Important Facts About Epithelioid Mesothelioma

  • Epithelioid mesothelioma is a commonly diagnosed cell type for this cancer, as it is present in 70% of cases.
  • There are many mesothelioma treatment options available for patients with epithelioid mesothelioma.
  • Patients with this cell type typically have promising survival rates, especially following successful mesothelioma surgery.

What Is Malignant Epithelioid Mesothelioma?

Epithelioid mesothelioma, a subtype of the rare cancer mesothelioma, is the result of mutated mesothelial cells. Specialists analyze the cells to determine the cell type present in the patient’s body, which can be epithelioid, sarcomatoid or a combination of both (biphasic).

Mesothelial cells genetically mutate due to irritation caused by exposure to asbestos, which is the only known cause of mesothelioma. Once asbestos fibers enter the body, the toxic particles can become lodged in the mesothelium, which is the lining of the lungs, abdomen and heart.

The mesothelium is made up of healthy epithelial cells, which means irritation of the mesothelium impacts the epithelial cells. Diseased epithelial cells of the mesothelium can turn into mesothelioma tumors.

Epithelioid Cell Type
Epithelioid Cell Type

Epithelioid Cell Type

Patients with this cell type of mesothelioma often have a better prognosis and more treatment options than people with sarcomatoid mesothelioma or biphasic mesothelioma. Epithelioid cells are easy to identify and remove during surgery. They also metastasize (spread) slower.

Characteristics of Epithelioid Mesothelioma Cells

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Cell Prevalence

The epithelioid mesothelioma cell type accounts for between 50% and 70% of mesothelioma cases.

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Cell Description

Epithelioid cells have a clearly defined, elongated egg-shape. They often clump together and have a pink cytoplasm. The cells’ visible nuclei make them easily distinguishable.

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Cell Behavior

These cells divide faster than the other cell types, contributing to faster tumor growth. However, the cells stick to each other, which slows metastasis and makes them easier to remove during surgery.

What Causes Epithelioid Mesothelioma?

Epithelioid cells form when healthy epithelial cells are irritated, leading to cell mutation and tumor formation. Asbestos exposure causes irritation to the healthy cells in the body, causing them to mutate into cancerous tumors.

The human body is made up of four types of cells: epithelial cells, nerve cells, muscle cells and connective tissue cells. Epithelial cells are found in the linings of the lungs, abdomen and heart. The lining of these organs is called the mesothelium.

When asbestos fibers infiltrate these linings, they become lodged in the mesothelium, irritating the healthy mesothelial cells and causing genetic mutation and tumor formation. This is how mesothelioma forms. The healthy epithelial cells affected by asbestos can become malignant and turn into epithelioid cells.

Epithelial cells line the thin membrane just outside of the lung cavity, abdominal cavity and heart
Epithelial cells line the thin membrane just outside of the lung cavity, abdominal cavity and heart

Mesothelial cells make up the thin linings around the lungs, inside the chest wall and the abdominal cavity, called the mesothelium.

Epithelial cells can transform into sarcomatoid cells when they become cancerous
Epithelial cells can transform into sarcomatoid cells when they become cancerous

Asbestos fibers can remain in the body for more than a decade, causing inflammation and cell damage. Genetic changes can occur in the mesothelial cells resulting in the development of the rare cancer, mesothelioma.

When mesenchymal cells become cancerous, they are called sarcomas
When mesenchymal cells become cancerous, they are called sarcomas

Epithelioid mesothelioma is the most common type of mesothelioma. The epithelioid mesothelioma cells often form multiple nodules within the mesothelium lining.

Epithelioid Mesothelioma Diagnosis

In order to provide a diagnosis, doctors will first perform a biopsy to extract tissue from the area where the cancer has formed. For instance, in cases of epithelioid pleural mesothelioma, doctors will take a biopsy from the lining of the lungs. In cases of epithelioid peritoneal mesothelioma, the biopsy will be taken from the lining of the abdomen.

Once the tissue biopsy is performed, doctors begin the process of histology, which is the microscopic study of tissue samples for the presence of cancer. After histology tests confirm the presence of cancer, the test results are provided through a pathology report, which identifies the specific types of cells found in the samples.

Epithelioid Mesothelioma Diagnosis Icon

Epithelioid Mesothelioma Diagnosis

A pathologist will use a process called immunohistochemistry to confirm the patient’s mesothelioma diagnosis. Immunohistochemistry is a process to identify antigens in cells.

The immunohistochemical markers include:

Calretinin Demonstrated in nearly all cases
Cytokeratin 5 or 5/6 Expressed in between 75% and 100% of cases
Wilms’ tumor-I antigen (WT1) Shown in between 70% and 95% of cases
Podoplanin (D2-40) Demonstrated in between 90% and 100% of cases

Epithelioid Mesothelioma Symptoms

Symptoms associated with epithelial mesothelioma are dependent on where the mesothelioma forms, such as in the lungs or the abdomen.

pleural mesothelioma icon

Symptoms of epithelioid pleural mesothelioma include:

  • Shortness of breath
  • Chest or lower back pain
  • Coughing
  • Difficulty swallowing
  • Arm or face swelling
  • Pleural effusions
peritoneal mesothelioma icon

Symptoms of epithelioid peritoneal mesothelioma include:

  • Abdominal pain
  • Nausea
  • Vomiting
  • Constipation
  • Bowel issues
  • Ascites (fluid in the abdomen)
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Epithelioid Mesothelioma Treatment Options

Patients diagnosed with epithelioid mesothelioma are often eligible for more treatment options than the other cell types. These tumors typically respond well to treatment. The primary treatments are surgery, chemotherapy and immunotherapy. However, many factors can affect a patient’s specific treatment plan, especially the type of mesothelioma.

Epithelioid Mesothelioma Surgery Icon

Epithelioid Mesothelioma Surgery

There are three primary surgical options for malignant mesothelioma.

Patients with epithelioid pleural mesothelioma have two surgical options: extrapleural pneumonectomy and pleurectomy with decortication.

Extrapleural pneumonectomy (EPP) involves the removal of the affected lung, the pleura, potentially the pericardium (sac around the heart) and part of the diaphragm.

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A study published in the Annals of Thoracic Surgery showed the effectiveness of EPP surgery for cases of epithelioid mesothelioma. The average survival time was 20.6 months.

Pleurectomy with decortication (P/D) does not remove the lung but does remove the pleura and possibly the pericardium and diaphragm. P/D is attributed to better quality of life for patients since neither lung is removed.

Epithelioid peritoneal mesothelioma patients only have one surgical option: cytoreduction with hyperthermic intraperitoneal chemotherapy (HIPEC). This two-part procedure begins with cytoreduction (debulking), which removes as many mesothelioma tumors as possible by resecting the peritoneum and, if needed, part of the intestines or other affected abdominal organs. The second part of the surgery is administering heated intraperitoneal chemotherapy directly into the abdomen.

Chemotherapy, Immunotherapy, Radiation and Emerging Epithelioid Mesothelioma Treatment Methods Icon

Chemotherapy, Immunotherapy, Radiation and Emerging Epithelioid Mesothelioma Treatment Methods

Mesothelioma specialists use other methods to treat patients diagnosed with mesothelioma. Chemotherapy, immunotherapy and radiation are the standard forms.

Chemotherapy is a common treatment method. Pemetrexed and cisplatin are the chemotherapy drugs approved by the FDA for mesothelioma treatment.

Immunotherapy is an emerging option for malignant mesothelioma treatment. Opdivo, Yervoy and Keytruda are FDA-approved immunotherapy drugs specifically for epithelioid pleural mesothelioma, but doctors support the use of immunotherapy for other types of mesothelioma.

Radiation is often used as a second-line treatment for epithelioid pleural mesothelioma. It is not used for other types of mesothelioma due to the increased risk of damaging nearby vital organs. Radiation beams can damage the organs and lead to further health issues.

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The Orphanet Journal of Rare Diseases published a report that radiation therapy combined with EPP increases epithelioid patients’ median survival to 33 months (nearly three years).

There have also been some successes in clinical trials with alternative treatment options, such as gene therapy, photodynamic therapy and oncolytic viruses.

Subtypes of Epithelioid Mesothelioma

There are subtypes of epithelial cells. The epithelioid subtypes have different sizes, shapes and structures. They all contain epithelial cells; however, these subtypes may react differently to treatment. The majority of these subtypes are rare and often benign.

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The five subtypes of epithelioid mesothelioma are:

  • Adenoid
  • Small cell
  • Cystic
  • Papillary
  • Deciduoid

Epithelioid Mesothelioma Prognosis

The prognosis for this cell type is typically the best out of the other cell types. The prognosis can range from 10-20 months. According to the Orphanet Journal of Rare Diseases, most patients who survive for two years after their diagnosis have this specific mesothelioma cell type.

Patients can have varying life expectancies. Epithelioid pleural mesothelioma is most commonly diagnosed. However, epithelioid peritoneal mesothelioma usually has a more promising prognosis.

A mesothelioma prognosis is determined by many factors, but the main factor to consider is whether the patient has been diagnosed with pleural or peritoneal:

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According to a study published on UpToDate, epithelioid pleural mesothelioma patients survived for an average of 19 months.

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Epithelioid peritoneal mesothelioma patients survived for an average of 55 months.

Other factors, like age, stage of mesothelioma and overall health, can impact a patient’s life expectancy.

There are many ways patients can improve their survival. One way is seeing a specialist or opting for new treatments. Connect with one of our patient advocates, registered nurse Karen Ritter, at karen@mesotheliomaguide.com for help finding a mesothelioma specialist or clinical trial.

Frequently Asked Questions About Epithelioid Mesothelioma

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What does epithelioid mesothelioma look like?

Epithelioid cells have a clear egg shape. They have a visible pink cytoplasm (the cell area surrounding the nucleus) and clump together with defined borders. These cells also have visible, dark-colored nuclei.

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How common is epithelioid mesothelioma?

Epithelioid mesothelioma occurs in at least 50% of all cases of this cancer. There are around 3,000 diagnosed mesothelioma cases in the United States each year, which means there are at least 1,500 epithelioid cases.

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What is the survival time for epithelioid mesothelioma?

Patients diagnosed with epithelioid mesothelioma have the best prognosis of the three cell variations. Pleural mesothelioma patients live for an average of 19 months after diagnosis. Peritoneal mesothelioma patients survive for an average of 55 months.

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How is epithelioid mesothelioma treated?

There are typically more treatment options available for patients with epithelial mesothelioma compared to the other cell types. The cells stick together, which helps doctors remove large chunks of cells and tumors during surgery. Chemotherapy, immunotherapy, radiation, tumor treating fields and other options are all used to treat mesothelioma.

Sources & Author

  1. About Malignant Mesothelioma. American Cancer Society. Retrieved from: https://www.cancer.org/content/dam/CRC/PDF/Public/8733.00.pdf. Accessed: 10/01/19.
  2. Epithelioid Cell. ScienceDirect. Retrieved from: https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/epithelioid-cell. Accessed: 10/04/19.
  3. Mesothelioma versus adenocarcinoma. Pathology Outlines. Retrieved from: http://www.pathologyoutlines.com/topic/pleuramesovsadeno.html. Accessed: 04/17/19.
  4. Signs and Symptoms of Mesothelioma. American Cancer Society. Retrieved from: https://www.cancer.org/cancer/malignant-mesothelioma/detection-diagnosis-staging/signs-symptoms.html. Accessed: 10/04/19.
  5. Immunohistochemistry. National Cancer Institute. Retrieved from: https://www.cancer.gov/publications/dictionaries/cancer-terms/def/immunohistochemistry. Accessed: 10/04/19.
  6. Guidelines for Pathologic Diagnosis of Malignant Mesothelioma. International Mesothelioma Interest Group. Retrieved from: https://www.archivesofpathology.org/doi/pdf/10.5858/arpa.2017-0124-RA. Accessed: 10/04/19.
  7. Long-term survival outcomes of cytoreductive surgery and perioperative intraperitoneal chemotherapy: Single-institutional experience with 1225 cases. Journal of Surgical Oncology. Retrieved from: https://www.ncbi.nlm.nih.gov/pubmed/31309588. Accessed: 07/29/19.
  8. Malignant mesothelioma. Orphanet Journal of Rare Diseases. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2652430/. Accessed: 10/04/19.
  9. Malignant Pleural Mesothelioma. Edited by Kenneth O’Byrne and Valerie Rusch. Oxford University Press. 2006.
Devin Golden

About the Writer, Devin Golden

Devin Golden is the senior content writer for Mesothelioma Guide. He produces mesothelioma-related content on various mediums, including the Mesothelioma Guide website and social media channels. Devin's objective is to translate complex information regarding mesothelioma into informative, easily absorbable content to help patients and their loved ones.