Mesothelioma Cell Types

There are three mesothelioma cell types: epithelioid, sarcomatoid, and biphasic. The specific cell type that a patient has been diagnosed with can greatly impact their treatment plans and their overall health outlook. Most patients will have epithelioid mesothelioma, which is the easiest of the three cell types to treat.

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What Are the Types of Mesothelioma Cells?

Malignant mesothelioma tumors are made up of one or more different types of cancer cells. The cell type that a patient has can greatly influence their health since some are more aggressive and harder to treat than others.

Because of these factors, doctors will want to see which type or types of cells make up a patient’s tumors.

The three cell types of mesothelioma are:

  • Epithelioid mesothelioma: This is the most common mesothelioma cancer cell type. These cells stick together, which means that this type spreads (metastasizes) more slowly than the other types.
  • Sarcomatoid mesothelioma: This is the least common type of mesothelioma cell. It’s also the most aggressive. Sarcomatoid mesothelioma cells can spread very quickly through the body, making them harder to treat.
  • Biphasic mesothelioma: Some tumors are made up of both epithelioid and sarcomatoid cells. When this happens, the patient has biphasic mesothelioma. Biphasic mesothelioma tumors are easier to treat if more epithelioid cells are present.

Oncologists (cancer doctors) can determine a patient’s mesothelioma cell type when making a diagnosis. From there, they can recommend cancer treatments that will work best depending on the cell type and other patient factors.

Our team can help you understand your options no matter which mesothelioma cell type you have. Learn more with our free mesothelioma guide.

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Key Facts About Types of Mesothelioma Cells

  • There are numerous mesothelioma cell subtypes that fall under the main types. Since the subtype can affect treatment outcomes, doctors must be sure they’ve properly diagnosed the patent before treatments start.
  • According to a report from the medical journal Translational Lung Cancer Research, a tumor must be made up of at least 10% of both epithelial and sarcomatoid cells to be considered biphasic.
  • It’s still not known why some people will develop one mesothelioma cell type and not another, as noted by a 2020 study from the journal Respiratory Research.
  • Asbestos exposure is the only known cause of all types of mesothelioma cells. The health risks of asbestos were known as far back as the 1930s. However, companies that made asbestos-containing products concealed the facts to keep their profit margins high.

Epithelioid Mesothelioma

Epithelioid mesothelioma (also known as epithelial mesothelioma) is the most common cell type. It accounts for about 70% of all mesothelioma cases, according to the UPMC Hillman Cancer Center.

Epithelioid mesothelioma develops when normal epithelial cells are mutated by asbestos fibers. Epithelial mesothelioma cells look like rectangles or cubes when viewed under a microscope.

Doctors can treat epithelioid mesothelioma more easily than the other cell types. Epithelioid mesothelioma cells multiply quickly but stick together instead of breaking off and possibly forming more tumors.

Epithelioid mesothelioma patients often live longer than those with sarcomatoid or biphasic mesothelioma since it doesn’t spread as quickly. The average life expectancy for these patients is 18 months.

There are also several subtypes of epithelioid mesothelioma. Which subtype a patient has may impact their treatment options and overall health.

Learn about common epithelial mesothelioma subtypes below.

Adenomatoid Mesothelioma

This is a rare type of cancer that’s found in only 6% of malignant pleural mesothelioma cases (when the cancer develops in the pleura, which is the lining of the lungs). It’s also known as glandular mesothelioma.

When viewed under a microscope, adenomatoid cells form in a lace pattern and have a ‘signet ring’ shape (round and/or boxy).

Adenomatoid mesothelioma cells may be mistaken for cells of benign (non-cancerous) adenomatoid tumors, according to the Journal of Medical Case Reports. Doctors must use extra care to avoid misdiagnosing patients as a result.

Cystic Mesothelioma

Cystic mesothelioma is typically found in cases of peritoneal mesothelioma, which forms in the abdomen lining (peritoneum). Most patients with cystic mesothelioma are women of reproductive age.

Cystic mesothelioma is unique because it’s actually benign at first. However, the tumors could possibly become cancerous if left untreated. Patients may even die from cystic mesothelioma that’s still benign without treatment, according to the medical journal Case Reports in Gastroenterology.

Deciduoid Mesothelioma

This mesothelioma cell type is quite rare — as of 2020, only around 50 cases have been reported in those with pleural mesothelioma.

At one time, deciduoid mesothelioma was thought to be more common in younger women with peritoneal mesothelioma. It’s now known that deciduoid cells appear in pleural mesothelioma and pericardial mesothelioma (which affects the heart lining) too.

Lymphohistiocytoid Mesothelioma

This form of mesothelioma is also very rare, accounting for under 1–3% of cases. It was once thought to be a subtype of sarcomatoid mesothelioma. It’s now considered a subtype of epithelial mesothelioma since patients with this type live as long as those with other types of epithelioid mesothelioma.

Lymphohistiocytoid mesothelioma could be mistaken for the cells of other cancers like non-Hodgkin’s lymphoma or sarcomatoid lung carcinoma under a microscope. Doctors need to carefully study the cells before diagnosing the patient.

If you’ve been diagnosed with any mesothelioma cell type, learn how we can help you by calling (888) 360-2406 now.

Small Cell Mesothelioma

Small cell mesothelioma was first mentioned in a 1992 medical report, and has since been classified as an epithelial mesothelioma subtype. Small cell mesothelioma looks like small cell lung cancer under a microscope.

Like many other subtypes of epithelial mesothelioma, it’s quite rare. In a study of 960 mesothelioma cases, only 8 of them were found to be small cell mesothelioma.

The same study also found that small cell mesothelioma patients have a low life expectancy. Patients with this cell type lived for just over 8 months on average after diagnosis.

Well-Differentiated Papillary Mesothelioma

This cell subtype is more common in younger women with peritoneal mesothelioma and men with testicular mesothelioma (which forms in the tunica vaginalis, or testicle lining). Well-differentiated papillary tumors grow in long, thin shapes that resemble fingers.

While all forms of mesothelioma are dangerous, those with this cell type may live for very long spans of time in some cases. The Journal of Medical Case Reports noted that a 60-year-old woman with well-differentiated papillary mesothelioma lived for 24 years after undergoing chemotherapy.

Sarcomatoid Mesothelioma

Sarcomatoid mesothelioma is the rarest of the three mesothelioma cell types, making up 10–20% of all cases.

Because of their spindle shape, sarcomatoid mesothelioma cells aren’t able to stick together like epithelial cells do. This means the cancer is more prone to metastasis (spreading) and is harder to treat.

As a result, sarcomatoid mesothelioma has the worst prognosis (health outlook) compared to the other mesothelioma cell types. These patients live for 7 months on average.

Like epithelioid mesothelioma, there are also a couple of different sarcomatoid mesothelioma subtypes.

Desmoplastic Mesothelioma

This subtype appears in up to 10% of all mesothelioma cases. It’s usually found in cases of pleural mesothelioma.

Desmoplastic mesothelioma cells are shaped like spindles and develop without a set pattern within a tumor.

Desmoplastic mesothelioma is tricky to diagnose as the tumors are made up of dense tissue that contains more benign cells than cancerous ones.

Transitional Mesothelioma

This type is quite unique as the cells don’t have characteristics of either sarcomatoid or epithelial cells. However, their genetic makeup is closer to sarcomatoid cells and patients with this cell type typically live as long as those with sarcomatoid mesothelioma.

Transitional mesothelioma cells are typically plump and long and grow in sheets.

Biphasic Mesothelioma

A patient has biphasic mesothelioma if doctors find both epithelial and sarcomatoid cells in a cancer tumor. Biphasic mesothelioma is the second-most common mesothelioma cell type. It accounts for 20–30% of mesothelioma cases, according to the American Cancer Society (ACS).

The ratio of epithelioid cells to sarcomatoid cells within a biphasic tumor greatly affects the patient’s prognosis. Patients have a better chance of living longer if more epithelioid cells are present as the cancer is less likely to grow quickly.

Biphasic mesothelioma patients also typically live longer than sarcomatoid mesothelioma patients do. The median life expectancy for biphasic patients is 10 months.

Types of Mesothelioma Cells and Treatment Options

Treatments are key to potentially living longer with mesothelioma, regardless of the cell type. Different mesothelioma treatment options may be recommended based on your cell type and other factors (like your overall health, where the cancer formed, and how far it spread).

While cases of sarcomatoid and biphasic mesothelioma are harder to treat, medical care is available for every mesothelioma cell type.

Commonly used treatments for all mesothelioma cell types include:

  • Chemotherapy: Chemotherapy (cancer-killing medications) can help patients with any mesothelioma cell type live longer. A 2021 study found that sarcomatoid mesothelioma patients lived nearly 11 months with chemotherapy — nearly half a year longer than average.
  • Immunotherapy: Immunotherapy medications help the body fight cancer more effectively. A 2021 report noted that patients with biphasic and sarcomatoid cells lived for over 18 months on average when treated with immunotherapy. Sarcomatoid and biphasic patients were studied as one group in this report.
  • Radiation therapy: Radiation allows doctors to kill cancer cells with beams of energy. A study from the medical journal Communications Biology found that epithelioid patients who received radiation therapy after surgery lived for 36 months on average. All of the patients in the study had pleural mesothelioma.
  • Surgery: Surgery is often the most effective mesothelioma treatment since it allows doctors to remove all of the cancer tumors they can see. It’s particularly effective in cases of epithelioid mesothelioma, according to mesothelioma specialist Dr. Joseph Friedberg.

Many of the treatments listed above are used together for best results. Further, doctors are also studying new treatments for every mesothelioma cell type in clinical trials.

Specialists at leading cancer centers will look at your mesothelioma cell type and other factors to create a treatment plan that may lead to a better prognosis.

Help for Your Mesothelioma Cell Type

All cell types of mesothelioma can be life-threatening — but medical care from doctors may improve your life expectancy and reduce your symptoms.

Further, while treating any mesothelioma cell type can be expensive, financial compensation may be available from the makers of asbestos-containing products. These companies knew that asbestos could lead to illnesses like mesothelioma but said nothing. You may be able to get a payout from them to cover your medical bills.

The Mesothelioma Resource Group can help patients find medical care and potentially access financial aid for all mesothelioma cell types. Learn how we can help with our free mesothelioma resource guide.

FAQs About Mesothelioma Cell Types

What are the three mesothelioma cell types?

The three types of mesothelioma cells are epithelioid, sarcomatoid, and biphasic mesothelioma. Epithelioid mesothelioma is by far the most common, and patients with this cell type often have a better health outlook than those with the other types.

There are also many different subtypes of mesothelioma cells, most of which are very rare.

What is mesothelioma histology?

Histology is the study of microscopic body structures, including cells and other tissues. Histology plays an important role in determining the type of mesothelioma cell a patient has.

Pathologists (doctors that examine fluid/tissue samples to diagnose patients) must be able to distinguish different types of mesothelioma cells from those of other cancer types. This is very important since mesothelioma is so rare (only 3,000 new cases per year).

If mesothelioma cells are misdiagnosed, the patient might not get the proper medical care they need. Having a deep knowledge of cancer histology is crucial to correctly identifying mesothelioma cells.

How do doctors diagnose mesothelioma cell types?

Doctors diagnose what type of mesothelioma cell is present by studying a biopsy under a microscope. A biopsy is a fluid or tissue sample extracted from a part of the body.

Pathologists must carefully study the sample to see which type of cell or cells are present. If they find epithelioid and/or sarcomatoid mesothelioma cells, they can confirm the mesothelioma diagnosis. If not, the patient may have another type of cancer or illness.

Mesothelioma Symptoms 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.

20 References
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