Mesothelioma Cell Types

Mesothelioma tumors can consist of two different types of cells, including epithelioid and sarcomatoid. Biphasic tumors contain both cell types. These cells look different under a microscope and behave differently, and this can affect a mesothelioma patient’s treatment options and overall life expectancy. For these reasons, it’s critical that a pathologist correctly identifies the types of cells present when making a diagnosis.

Fact-Checked and Medically Reviewed By: Dr. Mark Levin

What Are the Major Types of Mesothelioma Cancer Cells?

Normal cells in the mesothelium (the lining of major body parts like the abdomen, lungs, testicles, or heart) can mutate into cancer after exposure to asbestos. These cells are called malignant mesothelioma cells.

There are three main mesothelioma cell types: 

  • Epithelioid cells: Most mesothelioma tumors are made up of epithelioid cells. This cell type is the easiest to treat.
  • Sarcomatoid cells: These rare cells are recognized by their large size and spindle shape. It is the hardest mesothelioma cell type to treat.
  • Biphasic tumors: Biphasic tumors contain both epithelioid and sarcomatoid cells. Which cell type is dominant will determine how fast the tumors spread and respond to treatment.

Each mesothelioma cell type responds differently to specific treatments, so correctly identifying the cell type is key to effective treatment.

For instance, a combination of surgery, chemotherapy, and radiation (called multimodal treatment) is the most commonly used treatment plan for epithelioid cells. Surgery and chemotherapy are frequently used to treat sarcomatoid cells.

The Mesothelioma Hope team can help you no matter which mesothelioma cell type you have. Our team has relationships with top doctors treating all mesothelioma cell types and can also help you cover expenses that stem from your diagnosis. Learn more with our Free Mesothelioma Guide.

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Quick Facts About Mesothelioma Cell Types

  • Epithelioid cells make up more than half of mesothelioma diagnoses and have a better prognosis (the expected outlook of the disease) than the other cell types, according to the American Cancer Society (ACS).
  • The ACS states that sarcomatoid cells account for 10-20% of mesothelioma cases.
  • Biphasic tumors make up the remainder of cases (20-30%), according to the ACS.
  • The National Cancer Institute (NCI) notes that mesothelioma cell types can be determined under a microscope through what is called a cytologic exam.

Epithelioid Mesothelioma

An illustration of microscopic epithelioid mesothelioma cells
Illustration of epithelioid cells under a microscope

Epithelioid cells are the most common mesothelioma cell type. Epithelioid mesothelioma cells are characterized by a single nucleus, a rectangular shape, and slow growth. Doctors use the term “epithelioid” and “epithelial” interchangeably when talking about this type of cancer cell.

Types of Epithelioid Mesothelioma Cells

There are several subtypes of epithelial cells depending on where they are found within the body. Learn about each type below.


This is a very rare epithelial mesothelioma subtype, found in just 6% of pleural mesothelioma cases. What makes this type so dangerous is that the cells can be mistaken for general adenomatoid tumors, which are benign (non-cancerous).

Thus, doctors need to be careful and make absolutely sure that their diagnosis is correct. Misdiagnosing adenomatoid mesothelioma as a benign tumor can have deadly consequences.


This is an extremely rare mesothelioma cell type, with only 200 reported cases across the country. Because of this, doctors still do not fully understand this cancer type.

Fortunately, these cells are usually benign. In fact, only one death has been reported from cystic mesothelioma.


One of the most aggressive epithelioid mesothelioma cell types, deciduoid mesothelioma cells are shaped like large polygons or ovals and have clearly defined borders. It’s found in less than 5% of all mesothelioma cases.


In this subtype, cells from the immune system bundle together in the mesothelium.

According to the medical journal Anticancer Research, it used to be considered a subtype of sarcomatoid mesothelioma. However, since patients with lymphohistiocytoid mesothelioma often live as long as those with other epithelioid subtypes, it was reclassified.

Papillary/Well-Differentiated Papillary

Papillary mesothelioma, also referred to as well-differentiated papillary mesothelioma (WDPM), is a rare and often benign mesothelioma cell type.

While there is no clearly proven treatment for papillary mesothelioma, surgery, chemotherapy, or radiation are all possible options.

Small Cell

Small cell mesothelioma is typically found in the peritoneum (abdominal lining), but this cell type has also been found in the pleura (lung lining) and pericardium (heart lining). This cell type is sometimes mistaken for small cell lung cancer.

Researchers are still trying to understand if cases of small cell mesothelioma spread in the same way as other small cell cancers do.

Epithelioid Mesothelioma Prognosis and Treatment

Patients diagnosed with epithelioid mesothelioma have a relatively better prognosis when compared to other cell types. On average, patients with epithelioid mesothelioma live 1-2 years after diagnosis.

However, mesothelioma prognosis is also affected by other factors like the stage of the cancer when it’s found, the patient’s overall health, age, and where the cancer develops in the body. For these reasons, prognosis can vary with each patient.

These factors also affect what type of mesothelioma treatments patients can safely undergo. Patients with epithelioid mesothelioma are typically treated through a combination of surgery, chemotherapy, and/or radiation.

Types of Epithelioid Mesothelioma Treatment


Epithelioid Mesothelioma Treatment

Surgery is the most frequent solution for epithelioid mesothelioma because epithelioid cells spread slowly, and so the tumors are often contained to a single spot in the body. However, patients who are older or who have underlying health issues may not qualify for surgery.

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Epithelioid Mesothelioma Treatment

Chemotherapy uses medications to attack and kill tumors. It’s not as effective as surgery, but still a strong option for epithelioid mesothelioma tumors. A combination of medications, including pemetrexed and cisplatin or carboplatin, is the most common chemotherapy treatment for epithelioid mesothelioma.

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Epithelioid Mesothelioma Treatment

Through radiation therapy, electrons are aimed at the tumor to prevent cells from multiplying. Radiation alone cannot fully treat mesothelioma, but it can be used in combination with other treatment methods. It’s also used to lessen pain and reduce symptoms.

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Multimodal Treatment

Epithelioid Mesothelioma Treatment

Specialists generally agree that some combination of surgery, chemotherapy, and radiation is the most effective method of improving epithelioid mesothelioma prognosis. This is known as multimodal treatment or therapy.

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Sarcomatoid Mesothelioma

An illustration of microscopic sarcomatoid mesothelioma cells
Illustration of sarcomatoid cells under a microscope

Sarcomatoid mesothelioma cells are much more aggressive than epithelioid cells. Unlike epithelioid cells, sarcomatoid mesothelioma cells don’t clump into masses. More often they create small nodules that quickly spread throughout the body.

Sarcomatoid cells are large and shaped like spindles. Often, they will combine into fibrous-looking bundles.

The small size of sarcomatoid mesothelioma cells and their resemblance to other types of cancer cells makes them difficult to diagnose properly. Fortunately, this is the least common of all mesothelioma cell types, so not as many patients are affected.

Types of Sarcomatoid Mesothelioma Cells

The following cell subtypes are most commonly found in sarcomatoid cells.

  • Chondrosarcomatous: Spindle-shaped cartilage cells growing in the mesothelium cause this subtype to form.
  • Desmoplastic: These cells account for about 5-10% of malignant pleural mesothelioma cases. It has a poor prognosis and is one of the more difficult subtypes to diagnose.
  • Osteosarcomatous: This extremely rare subtype forms when cancerous bone cells lodge in the mesothelium.

Sarcomatoid Mesothelioma Prognosis and Treatment

Sarcomatoid mesothelioma frequently forms as small nodules, and it can quickly spread from its origin point to nearby organs. It is also the most difficult mesothelioma cell type to treat, with an average life expectancy of seven months.

Some treatment options may be available to improve a patient’s prognosis depending on if the cancer is caught before it has spread throughout the body.


Surgery can be performed on sarcomatoid mesothelioma patients whose cancer hasn’t spread very far.

In a 2019 study of pleural sarcomatoid mesothelioma patients, those who underwent surgery lived for roughly 7.5 months on average, while those who didn’t lived for just over 4 months on average.


Sarcomatoid cells usually receive the same chemotherapy combinations as the other types of mesothelioma, which is a combination of pemetrexed and cisplatin or carboplatin.

A 2021 study noted that sarcomatoid pleural mesothelioma patients lived for nearly 11 months on average when treated with chemotherapy.

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Biphasic Mesothelioma

An illustration of microscopic biphasic mesothelioma cells
Illustration of biphasic cell types microscope

Tumors formed by a combination of sarcomatoid and epithelioid cells are called biphasic tumors, or sometimes “mixed mesothelioma.” There are no biphasic cells. This type accounts for 20-30% of mesothelioma cases.

A common method for identifying biphasic mesothelioma tumors is called immunohistochemistry. This involves coating cell walls with dye to make the proteins within cells more visible. A trained specialist can determine which mesothelioma cell type is dominant based on these proteins.

Biphasic Mesothelioma Prognosis and Treatment

The prognosis for biphasic mesothelioma is about 10 months, but some patients have more or less time to live depending on the treatments they receive. Which mesothelioma cells are dominant will affect how this type spreads and responds to treatments.

A higher percentage of sarcomatoid cells means that biphasic mesothelioma may spread faster through the body, which can limit a patient’s treatment options.

Further, sarcomatoid cells respond poorly to treatment, which can make biphasic mesothelioma harder to treat.

Which therapies will be used to treat biphasic mesothelioma depends on the ratio of epithelioid to sarcomatoid cells, as well as where the cancer has developed, how far it has spread, and individual patient factors.

Mesothelioma Histology and Determining Cell Type

The broad term for studying any type of tissue is called histology. It is used in every type of cancer diagnosis, including mesothelioma.

Histology is very important when diagnosing and treating mesothelioma. By determining which cells are present, doctors can form specialized treatment plans that give patients the best chance of achieving long-term recovery.

How Mesothelioma Cell Type is Determined

Testing for mesothelioma begins with X-rays and CT scans of the chest or abdomen. If those tests show cause for concern, a biopsy will be conducted.

Through a biopsy, a mesothelioma specialist takes a fluid or tissue sample and examines it under a microscope. Through this, the specialist can determine if there are cancerous cells and if so, what type of cells are present. A biopsy is the only way to confirm a mesothelioma diagnosis.

Getting Help for Your Mesothelioma Cell Type

No matter what mesothelioma cell type you are diagnosed with, there are treatment options available for you. It’s critical that you work with a mesothelioma specialist who can help determine the best mesothelioma treatments available for you.

These specialists can also help you by confirming your cell type before treatment begins. This is extremely crucial because mesothelioma cells closely resemble other cancers, meaning you could be misdiagnosed by a non-specialist.

To learn more about mesothelioma cell types — and how they impact diagnosis and treatment options — get your Free Mesothelioma Guide.

Mesothelioma Cell Types FAQs

What are the three cell types of mesothelioma?

The three main mesothelioma cell types are epitheloid, sarcomatoid, and biphasic mesothelioma.

Epithelioid mesothelioma is the most common and easiest to treat, while sarcomatoid is the opposite — it responds poorly to treatments and is the rarest type.

A cancer tumor can have both epitheloid and sarcomatoid cells, in which case the patient has biphasic mesothelioma.

What are mesothelioma cells?

Mesothelioma cells are mutated versions of healthy mesothelial cells, which are found in the linings of major body parts like the lungs, abdomen, heart, or testicles.

Mesothelioma cells can develop 10-50 years after exposure to asbestos.

There are two main mesothelioma cell types. The first major type is epithelioid, which spreads more slowly, is more common, and is easier to treat. The other type is sarcomatoid mesothelioma, which is very aggressive and quite rare.

Some tumors have both types of mesothelioma cells present, and these cases are considered biphasic mesothelioma.

Does mesothelioma have spindle-shaped cells?

In some cases, yes. Sarcomatoid mesothelioma cells, which are very hard to treat, are shaped like spindles.

Sarcomatoid mesothelioma cells don’t stick together very well because of their spindle shape. Because of this, these cells are more likely to spread through the body.

This is why sarcomatoid mesothelioma patients often have a very poor prognosis when compared to the other mesothelioma cell types.

Does mesothelioma cell type impact my treatment options?

Possibly, yes. In general, sarcomatoid mesothelioma patients have fewer treatment options available than those with the other cell types since it’s so aggressive.

That said, other factors like where your cancer develops, if it has spread, and how your health is besides having cancer can all impact what treatments you receive.

In general, you’re more likely to get life-extending treatments like surgery or chemotherapy if you are diagnosed with early-stage mesothelioma and do not have the sarcomatoid cell type.

Why do people develop different mesothelioma cell types?

Doctors are still unsure as to why there are different mesothelioma cell types, according to a 2020 report from the medical journal Respiratory Research.

The good news is that doctors can develop treatment plans for any mesothelioma cell type to help you live as long as possible.

What happens to your cells when you have mesothelioma?

When you have mesothelioma, healthy cells within the linings of major organs (like the lungs, abdomen, heart, or testicles) have mutated into cancerous ones due to asbestos exposure.

These mesothelioma cells grow at an out-of-control rate and form tumors that overrun the body without treatment. However, you can get treatments to slow the spread of these cancer cells with help from specialized mesothelioma doctors.

Reviewed by:Dr. Mark Levin

Certified Oncologist and Hematologist

  • Fact-Checked
  • Editor

Mark Levin, MD has over 30 years of experience in academic and community hematology and oncology. In addition to serving as Chief or Director at four different teaching institutions throughout his life, he is also still a practicing clinician, has taught and designed formal education programs, and has authored numerous publications in various fields related to hematology and oncology.

Dr. Mark Levin is an independently paid medical reviewer.

  • Board Certified Oncologist
  • 30+ Years Experience
  • Published Medical Author
Written by:

Lead Editor

Laura Wright is a journalist and content strategist with more than 15 years of professional experience. She attended college at the University of Florida, graduating magna cum laude with a bachelor’s degree in journalism in 2008. Her writing has been featured in The Gainesville Sun and other regional publications throughout Florida.

8 References
  1. Amin, W., Linkov, F., Landsittel, D., Silverstein, J., Bashara, W., Gaudioso, C., . . . Becich, M. (2018, August 3). Factors influencing malignant mesothelioma survival: A retrospective review of the National Mesothelioma Virtual Bank cohort. Retrieved December 2, 2022, from

  2. Ko, H., Kamil, Z., & Geddie, W. (2014, June 12). Microcystic variant malignant mesothelioma presenting as a localized paraspinal mass. Retrieved December 2, 2022, from

  3. Kottangal, G., et al. (2022, May). Pleural malignant deciduoid mesothelioma: Case report of a rare variant of epithelioid mesothelioma. Retrieved December 2, 2022, from

  4. Matsubara, T., Toyokawa, G., Yamada, Y., Nabeshima, K., Haratake, N., Kozuma, Y., . . . Maehara, Y. (2017, December 01). A case of the resected lymphohistiocytoid mesothelioma: BAP1 is a key of accurate diagnosis. Retrieved December 2, 2022, from

  5. Moffitt Cancer Center. (n.d.). Sarcomatoid mesothelioma, symptoms & treatment. Retrieved December 2, 2022, from

  6. Schipper, P., Verma, V., Bueno, R., Burt, B., Wolf, A., Baud, M., . . . Bovolato, P. (2018, September 29). Is there a role for cancer-directed surgery in early-stage sarcomatoid or biphasic mesothelioma? Retrieved December 2, 2022, from

  7. National Cancer Institute. (n.d.). Malignant Mesothelioma. Retrieved December 2, 2022, from

  8. U.S. National Library of Medicine. (n.d.). Deciduoid mesothelioma: report of 21 cases with review of the literature. Retrieved December 2, 2022, from

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