Written By: Devin Golden

Epithelioid Mesothelioma

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


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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 epithelioid mesothelioma patients.
  • Patients with this cell type typically have promising survival rates, especially following successful mesothelioma surgery.

What Is Epithelioid Mesothelioma?

epithelioid cell

Epithelioid Cell Type

Epithelioid mesothelioma, a subtype of the rare cancer mesothelioma, is the result of mutated mesothelial cells. Specialists analyze the cells to determine the mesothelioma 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.

Patients with epithelioid 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

cell prevalence

Cell Prevalence

Epithelioid mesothelioma accounts for between 50% and 70% of mesothelioma cases.

cell description

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.

cell behavior

Cell Behavior

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

Epithelioid Mesothelioma Symptoms

Epithelioid cells closely resemble cell types of adenocarcinoma, which is a type of cancer forming in organs like the lungs, colon and breast. Symptoms of epithelioid mesothelioma are dependent on where the mesothelioma forms, such as pleural mesothelioma (in the lining of the lungs) or peritoneal mesothelioma (in the lining of the abdominal cavity).

Epithelioid pleural mesothelioma symptoms include:

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

Epithelioid peritoneal mesothelioma symptoms include:

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

In order to diagnose epithelioid mesothelioma, 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.

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 for epithelioid mesothelioma include:


Demonstrated in nearly all epithelioid mesothelioma 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

Treatment Options for Epithelioid Mesothelioma

Epithelioid mesothelioma often has more treatment options than the other mesothelioma cell types. The primary treatment options for epithelioid mesothelioma are surgery, chemotherapy and immunotherapy. However, many factors can affect a patient’s specific treatment plan, especially the type of mesothelioma. For instance, epithelioid pleural mesothelioma and epithelioid peritoneal mesothelioma are treated differently.


Epithelioid Mesothelioma Surgery

There are three primary surgical options for epithelioid mesothelioma.

Epithelioid pleural mesothelioma patients 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.

A study published in the Annals of Thoracic Surgery showed the effectiveness of EPP surgery for epithelioid mesothelioma patients. 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 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.


Epithelioid Mesothelioma Therapies and Other Treatment Methods

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

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

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

Radiation therapy is often used as a second-line treatment for epithelioid pleural mesothelioma. It is not used for epithelioid peritoneal mesothelioma due to the vital organs in the abdominal cavity. Radiation beams can damage the organs and lead to further health issues.

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

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

The five subtypes are:

  • Adenoid
  • Small cell
  • Cystic
  • Papillary
  • Deciduoid

Epithelioid Mesothelioma Prognosis

The prognosis for epithelioid mesothelioma is typically the best out of the other cell types. An epithelioid mesothelioma 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 epithelioid mesothelioma.

Patients with epithelioid mesothelioma can have varying life expectancies. Epithelioid pleural mesothelioma is more common than epithelioid peritoneal mesothelioma. However, epithelioid peritoneal mesothelioma usually has a more promising prognosis than epithelioid pleural mesothelioma.

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

  • According to a study published on UpToDate, epithelioid pleural mesothelioma patients survived for an average of 19 months.
  • 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 with epithelioid mesothelioma 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 mesothelioma cells have a clear egg shape. They have a visible pink cytoplasm (the cell area surrounding the nucleus) and clump together with defined borders. Epithelioid 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. This cell type can occur in both pleural mesothelioma and peritoneal mesothelioma.

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What is the survival time for epithelioid mesothelioma?

This mesothelioma cell type has 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 epithelioid mesothelioma. 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 epithelioid 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 a 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.