Written By: Karen Selby, RN,
Last modified: November 13, 2021

What Is Epithelial Mesothelioma?

Epithelial mesothelioma is the most common of the three cell types of mesothelioma cancer. This tumor cell type involves cuboid cells with low mobility that group together and have visible nuclei. Epithelial and epithelioid both refer to this type of asbestos-related cancer.

The epithelial mesothelioma cell type is receptive to cancer treatment compared to other cell types

More than 50% and up to 70% of mesothelioma cases are epithelioid. Epithelial cells line the portion of the airway known as the bronchus, an area susceptible to asbestos inhalation. The respiratory tract lining consists of pseudostratified columnar ciliated epithelium, which serves as a protective barrier. 

Patients with this tumor cell type live about six months longer than patients with other cancer cell types. It has the best prognosis of the three mesothelioma cell types because it is the most responsive to treatment. Due to this higher response rate, epithelioid cases tend to qualify for more aggressive and effective treatment plans.

Mesothelioma tumor location has a more significant impact than cell type on the kind of treatments a patient will undergo. However, cell types such as epithelial sarcomatoid or biphasic affect whether patients qualify for specific aggressive therapies.

Characteristics of Epithelial Cells

Epithelial mesothelioma cells clump together in groups. Each cell is square, cubed, columnar (long) or squamous (flat) in appearance. The nucleus, the central cellular region that contains genetic material, is noticeably visible in each cell.

Because epithelioid cells lack mobility and adhere closely together, they are less likely to spread and metastasize than sarcomatoid cells. This characteristic is one of the reasons epithelial mesothelioma has a better prognosis than other cell types.

Symptoms of Epithelial Cell Mesothelioma

Mesothelioma symptoms remain the same regardless of the cells that make up tumors. Tumor cell types primarily impact treatment response and growth rate, but they do not influence symptoms. Epithelioid tumor cells do not cause symptoms different from other cell types.As cancer grows and spreads, symptoms appear when organs such as the lungs, heart or kidneys are affected. Initial symptoms of pleural or peritoneal mesothelioma include cough, shortness of breath and lack of appetite. As the disease progresses, more severe symptoms may surface.

  • Shortness of breath
  • Persistent, nonproductive (dry) cough
  • Hoarseness
  • Coughing up blood
  • Low blood oxygen levels
  • Anemia (low iron)
  • Fever
  • Night sweats
  • Weight loss
  • Feeling full, even without eating
  • Lack of appetite and nausea
  • Fatigue and extreme tiredness
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Prognosis for Epithelial Mesothelioma

According to data published in 2018 from the National Mesothelioma Virtual Bank, the median survival of epithelioid patients is 18 months. This life expectancy measures the time from diagnosis until death. Patients with biphasic cell type have a median survival of 10 months, and life expectancy is seven months for people with sarcomatoid cells.

Compared with other cell types, patients with epithelioid cells had an improved prognosis of around 200 additional days of survival. This enhanced survival rate can add years to a patient’s life expectancy if they receive an early-stage diagnosis with aggressive treatment.

According to a 2020 study published in Oncology Reports, epithelioid mesothelioma prognosis depends on a protein called CTGF, or connective tissue growth factor. Patients with lower levels of this protein had a better prognosis and more prolonged survival.

Epithelial cell type allows patients to access more aggressive treatment plans, such as surgery, and innovative clinical trials, especially when treated at a mesothelioma specialty clinic.

Epithelial cell type by far is the best malignant mesothelioma cell type to have. This patient will definitely have more options such as surgery and is more likely to respond to treatment. The survival rate for epithelial patients is overall significantly longer.
Karen Selby, R.N.
Patient Advocate

Epithelial Mesothelioma Diagnosis

Accurately diagnosing epithelioid mesothelioma requires multiple steps. Many patients experience significant delays between the onset of symptoms and receiving an accurate diagnosis.

When symptoms first appear, such as cough or shortness of breath, they can be vague and prompt general practitioners to order several tests to rule out other illnesses. Eventually, after radiology exams and a biopsy procedure, a mesothelioma specialist can confirm a diagnosis with a tumor cell type.

Challenges

Several obstacles may delay your physician from obtaining a tissue sample. Mesothelioma patients wait approximately three months after symptoms appear before they receive a diagnosis. 

Only a tumor biopsy, collected through a procedure such as a thoracoscopy or fine-needle aspiration, leads to accurate identification of epithelioid mesothelioma.

  • Initial symptoms such as cough and fatigue mimic less severe respiratory conditions, according to research in the 2019 Expert Review of Respiratory Medicine.
  • Primary care doctors perform in-office exams and tests to rule out common causes of symptoms before referring a patient for more thorough chest scans.
  • Even with a referral, X-rays, CT scans or MRI tests can take weeks to schedule.
  • Radiological imaging can reveal visual abnormalities, but does not determine the cause of diseased chest areas.
  • Once imaging results are available, it may still take several more weeks to schedule an appointment for a biopsy.

One of the most important things you can do to minimize diagnostic delays is to share any history of asbestos exposure with your health care provider.

If your doctor knows you have a history of asbestos exposure, they are more likely to consider mesothelioma or another asbestos-related condition.

Role of Immunotherapy in Diagnosis

Immunohistochemistry is a laboratory test to detect proteins on the surface of cells. These proteins help classify cancer cell types.

Pathologists use immunohistochemistry to identify epithelioid mesothelioma and differentiate it from another type of cancer called adenocarcinoma.

According to the 2018 ASCO pleural mesothelioma treatment guidelines, immunohistochemistry is the recommended test for suspected mesothelioma tumors.

This analysis will confirm the absence or presence of mesothelioma cell markers, leading to the most accurate diagnosis possible.

Your pathology results will show the specific cell type of your cancer. If you don’t have a record of your cell type, be sure to ask your doctor and request a copy of the pathology report for your records.

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Epithelial Mesothelioma Cell Subtypes

When a pathologist outlines their report for your treating physician, they provide a wide breadth of information. 

These details include the biopsy site where the sample originated, how the surgeon collected the sample, cell characteristics, the distribution of cells in the tissue and an overall diagnosis. 

Epithelial cells can vary in many different ways, leading to several additional cellular subtypes within this group. These subtypes can inform your doctor how your cancer might progress and which treatments may be most appropriate.

Tubulopapillary Mesothelioma Cell Sample
Tubulopapillary cells as seen under a microscope.

Tubulopapillary

This subtype of epithelioid mesothelioma is the most common. Most tubulopapillary mesotheliomas contain well-differentiated cells. Doctors without mesothelioma experience can mistake this for adenocarcinoma that has spread to the pleura.

Glandular Mesothelioma Cells
Mucus-secreting glandular cells stained for microscopic evaluation.

Glandular

Tumors with the glandular pattern are primarily composed of gland-like (acinar) structures. This subtype usually develops in the pleural lining. It may be confused with adenocarcinoma that has spread to the pleura.

Epithelial mesothelioma cells under a microscope.
Rare adenomatoid mesothelioma cell pathology.

Adenomatoid

Adenomatoid mesothelioma, also known as the microglandular cell type, accounts for 6% of pleural mesothelioma cases. These tumor cells appear flat or cube-like with a lining of small gland-like structures.

Adenomatoid cells often combine with other kinds of epithelial cells inside a tumor. Doctors may mistake it for benign adenomatoid tumors or metastatic adenocarcinoma of the pleura.

Solid Cell Variant
Pathology stain of solid epithelial cells.

Solid

The solid subtype has two patterns: Well-differentiated and poorly differentiated.

Solid, well-differentiated epithelial type is more common. It has round cells in nests, cords or sheets.

The poorly differentiated pattern has relatively unorganized cells that are polygonal (having straight sides) to round in appearance.

A pathologist without relevant experience may mistake solid, well-differentiated mesothelioma for benign reactive mesothelial hyperplasia. The poorly differentiated pattern looks like lymphoma and large cell carcinoma.

Deciduoid Mesothelioma Cell Type
Deciduoid mesothelioma cells stained for pathology.

Deciduoid

Deciduoid mesothelioma is a rare epithelial subtype. This pattern features large round to polygonal cells with sharp borders.

Deciduoid mesothelioma may be mistaken for squamous cell carcinoma, anaplastic large cell lymphoma, gastrointestinal autonomic nerve tumor, pseudotumoral deciduosis, trophoblastic neoplasia and the oxyphilic variant of ovarian clear cell carcinoma.

well-differentiated papillary mesothelioma
Pathology examination of well-differentiated papillary mesothelioma.

Well-Differentiated Papillary Mesothelioma

This cell type grows slowly and features small bumps or protrusions lined by a single layer of thin cells. This type of mesothelioma is primarily benign and responds well to surgery. It occurs mainly in younger and older adult women with peritoneal mesothelioma.

Epithelial Mesothelioma Treatment Options

Patients have a better chance of improving life expectancy when they seek out specialized mesothelioma care and treatments tailored to their diagnosis. The first step in finding the best mesothelioma treatment is to seek the advice of an expert physician.

Of the three mesothelioma types, epithelial responds best to treatment. Patients diagnosed with the epithelial variant tend to have more treatment and clinical trial options, such as immunotherapy and radiation therapy. 

Early-stage epithelioid mesothelioma is treated aggressively with a combination of surgery, chemotherapy and radiation therapy. According to a 2019 report in The Annals of Thoracic Surgery, combination therapy resulted in significantly better outcomes for patients with epithelial malignant pleural mesothelioma.

As cancer progresses it has a higher chance of spreading and metastasizing to other areas, making surgery less beneficial. Late-stage cases respond better to chemotherapy, immunotherapy and Tumor Treating Fields therapy.

Treatment Types and Median Survival for Epithelial Mesothelioma Patients

Treatment Type Median Survival
No Treatment 10.2 Months
Chemotherapy Alone 15.4 Months
Surgery Plus Chemotherapy 21.1 Months
Multimodal (all three) 21.7 Months
Source: The Annals of Thoracic Surgery, 2019

Common Questions About Epithelial Mesothelioma

How does a mesothelioma cell type affect my prognosis and treatment?

Patients with the epithelioid cell type have the most mesothelioma treatment options because their cell type responds the best to all forms of treatment. Epithelioid patients also live an average of 200 days longer than patients with other cell types.

How do I find a doctor who treats epithelial mesothelioma?

Most oncologists are not trained to treat epithelioid mesothelioma. Mesothelioma doctors have trained for years to specialize in the treatment of this cancer. Our Patient Advocates can help you find a top doctor who treats epithelial mesothelioma.


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