Mesothelioma Cells

What Are the Different Types of Mesothelioma Cells?

Mesothelioma tumors contain either epithelial, sarcomatoid or biphasic cells. Each type of mesothelioma cell influences how the tumor grows and responds to treatment. Identifying your mesothelioma cells empowers you and your doctor to make informed decisions to customize a treatment plan for you.

Key Facts About Mesothelioma Cells

1. A biopsy is crucial for diagnosing mesothelioma. It alone can determine the specific mesothelioma cell type.
2. Your tumor’s location and cell type will affect your treatment options.
3. A study on peritoneal mesothelioma found a median survival of 55 months for patients with epithelioid cells. Patients with sarcomatoid or biphasic cells had a median survival of 7 to 13 months.

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The most common cell type in mesothelioma cases is epithelioid, which makes up 50% to 70% of cases. They often form clusters or sheets of oval or cube-shaped cells with clear centers visible under a microscope. Sarcomatoid is rarer with spindle-shaped cells. Biphasic is a mix of epithelioid and sarcomatoid cells. There are also a few rare subtypes, but most cases fall into these three categories.

Studying mesothelioma cells and tissues under a microscope is called histology, which helps show their structure and behavior. Histology reveals key details about these mesothelioma cells, which are noted in your pathology report. 

Epithelial Cells

Epithelial or epithelioid mesothelioma cells are typically uniform with growth patterns that are somewhat predictable. Those with an epithelial cell type tend to have a better outlook or prognosis. These tumors aren’t as aggressive and respond well to intensive treatment regimens like surgery and chemo. 

Christine Shippen, a pleural mesothelioma survivor who was diagnosed with this specific type of mesothelioma, shared her advice for other survivors with us. She said, “Be advised by your doctor or oncologist what the best treatment is for you. There are other treatments available depending on how fit you are.”

Reflecting on her 6 years as a survivor, she added, “Give yourself time to come to terms if you can. The longer I live, I continue to thank God for giving me the willpower to believe I will fight the fight to the end. My perspective remains always positive.”

Sarcomatoid Cells

Sarcomatoid mesothelioma cells occur in only about 10% to 20% of cases. They’re generally associated with poor outcomes, though everyone responds to treatment differently. This is the most aggressive cell type. This can make treating sarcomatoid mesothelioma more challenging.

Sarcomatoid cells develop quickly and don’t respond as well to typical treatments. They may need more aggressive treatment protocols, and people with this cell type are often diagnosed at later mesothelioma stages.

Diagnosed with the sarcomatoid mesothelioma subtype, Wally Rogers far surpassed his initial prognosis. After experiencing serious side effects from chemo, Wally tells us he tried Keytruda, saying, “It’s a real mystery at this point why I’ve done so well. After listening to the medical people, it’s almost shocking. I’m not superhuman by any means. I’m a simple man. Maybe I can let people know, there is hope out there.”

Biphasic Cells

Biphasic mesothelioma cells are a combination of epithelial and sarcomatoid cells. This mixed cell type accounts for 20% to 30% of mesothelioma cases. To receive a biphasic diagnosis, each cell type must account for at least 10% of the tumor mass.

Since biphasic tumors consist of mixed cell types, they can be challenging to accurately diagnose based on smaller biopsies. Your treatment plan and outlook depend on which type is found in greater amounts in your biopsy sample.

Registered Nurse and Patient Advocate Karen Selby explains, “Cisplatin and carboplatin combination is usually the gold standard” for people with epithelioid mesothelioma cells. However, for people with sarcomatoid and biphasic mesothelioma cells, “immunotherapy is often the go to now.”

Rare Cell Types of Mesothelioma

Some mesothelioma tumors contain rare subtypes that don’t fall into one of the main categories. These unusual mesothelioma cell types can make diagnosis more complex and may influence how the cancer responds to treatment.

Rare Forms of Mesothelioma Cell Types

• Adenomatoid: A subtype of epithelial cells, these cells resemble gland-like structures and often appear in the peritoneum.
• Benign: Benign mesothelioma is neither cancerous nor the result of asbestos exposure.
• Cystic: Cystic mesothelioma is a subtype of epithelial with smooth, thin-walled cysts held together with fragile fibrovascular tissue.
• Deciduoid: Extremely rare and most often found in young women with peritoneal mesothelioma.
• Desmoplastic: Composed of dense, fibrous tissue, desmoplastic mesothelioma is typically grouped with sarcomatoid cases.
• Heterologous: Tumors of heterologous cell types contain bodily tissues different from those in which they form. Only a handful of cases exist in the medical literature.
• Lymphohistiocytoid: A subtype of sarcomatoid, lymphohistiocytoid mesothelioma mimics inflammatory or immune system tissue and may be confused with benign conditions.
• Small cell: Small-cell mesothelioma occurs when a large proportion of a mesothelioma tumor comprises small cells that grow in a pattern similar to small-cell carcinoma.
• Well-differentiated papillary: A variant of epithelial mesothelioma, papillary mesothelioma cells usually grow slowly and can resemble healthy cells.

These rare cell types often require advanced pathology testing. While there is no specific treatment protocol for each, doctors base treatment decisions on the cells’ dominant behavior and whether they act more like epithelial or sarcomatoid mesothelioma.

How Do Doctors Identify Mesothelioma Cell Types?

To find out your specific mesothelioma cell type, pathologists take a small piece of tissue from a biopsy. They look at it under a microscope using chemical stains that make the cells’ features stand out. They study the cells to see what they look like and how they function. 

Special tests, like immunohistochemistry, help doctors find specific markers on the cells. Knowing the cell type helps cancer doctors diagnose mesothelioma and choose the best treatment plan based on how the cancer might behave.

Other Ways Pathologists Learn About Mesothelioma Cells

Pathologists use special tests and advanced tools to study mesothelioma cells. These methods show detailed features of the cells’ structure, genes and proteins. They also reveal how the cells grow, change shape and interact with their surroundings. This helps doctors understand how aggressive the cancer might be, how it behaves and how it may respond to different strategies.

Tools for Studying Mesothelioma Cells

• Cell staining: Checks for specific proteins in mesothelioma cells using special stains to help with diagnosis and treatment choices.
• Electron microscope: This microscope shows a very clear and detailed picture of the cells to help tell mesothelioma apart from other cancers.
• Gene analysis: This test, called a cytogenetic test, checks if the cancer cells have changes in their chromosomes to help with diagnosis.
• Molecular testing: Finds gene changes that might respond to treatments like targeted therapy, which blocks genes that help mesothelioma cells grow and spread.
• Protein profiling: A test called flow cytometry checks proteins on cancer cells’ surfaces to see how the cells respond to treatments.

All of these assessments help to create a more complete understanding of mesothelioma cells. Your doctors use this information to understand how each individual mesothelioma case operates on a cellular level and develop a treatment plan that works best for you.

How Cell Type Affects Mesothelioma Prognosis and Treatment

Mesothelioma cell types affect outcomes because they change how cancer cells and their surroundings behave. Slower-growing types like epithelioid respond better to surgery and medicines because their tumors let treatments and the immune system work more easily. Faster-growing types like sarcomatoid build thick tissue that blocks treatment and immune system defenses, making them harder to treat. These differences also affect how well newer treatments, like immunotherapy, work.

When doctors look at biopsy results, they can decide if surgery is a good option or if relieving symptoms with palliative care is better. These results also help doctors and patients have clearer conversations about what’s ahead, allowing them to prepare with their families for their mesothelioma journey.

New treatments are helping some people with mesothelioma live longer. In a 2025 study in the International Journal of Clinical Oncology, immune checkpoint inhibitors Opdivo and Yervoy improved progression-free survival for almost 11 months in some people. Overall survival was significantly better in patients with the epithelial cell type. 

Common Questions About Mesothelioma Cells

What do mesothelial cells indicate?

Healthy mesothelial cells are those that line the lungs, the abdomen and the heart sac. They become malignant cancerous cells through asbestos exposure, which irritates the lining and instigates tumor growth.

Can mesothelioma have more than one cell type?

Yes. Biphasic mesothelioma has both epithelial and sarcomatoid cells within one tumor. The dominant type will determine the characteristics of the cancer and the treatment.

Do mesothelioma cell types change over time?

Generally, no. People with mesothelioma usually don’t have a different type over the course of their treatment or disease. Treatment response and the way tumors develop may vary throughout the progression of mesothelioma.

Is cell type more important than stage in mesothelioma prognosis?

Both mesothelioma cell type and how far the cancer has spread are important. Cell type informs aggressiveness and response to treatment, while stage indicates the ability to spread. They factor into prognosis upon first diagnosis and affect the care you’ll receive.

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