What Are the Different Mesothelioma Cell Types?

Mesothelioma Cell Types Explained

Generally, the types of mesothelioma cells can be significant in a patient’s prognosis and cancer treatment plan. About 60 percent of all mesothelioma (a form of cancer caused by asbestos exposure) cases are epithelioid. This cell type usually has a better prognosis than sarcomatoid, which accounts for about 25 percent of all cases. The remaining 15 percent of cases are biphasic, meaning a patient’s tumor exhibits both epithelioid and sarcomatoid cells. A biphasic diagnosis requires at least 10 percent of each cell pattern to be present in the tumor.

Epithelioid tumors originate in the cells that line an organ, whereas sarcomatoid tumors start growing in the bone or soft tissues. Sarcomatoid cells tend to metastasize faster than epithelioid cells, making epithelioid cases generally more treatable. Most patients with epithelioid tumors undergo a multimodal treatment plan (treatment approach that combines multiple therapies, such as chemotherapy and radiation) to eradicate their cancer.

It’s also important to remember that statistics are merely that: statistics. Statistics are numbers based on other patients, other circumstances of asbestos exposure, and other survival rates. And because mesothelioma is a rare form of cancer, these numbers are usually stale. As a patient, attitude matters. Accepting your diagnosis doesn’t mean you must accept your doctor-given prognosis. Many patients have outlived their original prognosis, and treatment options continue to advance as doctors learn more about this rare disease.

Types of Mesothelioma Cells

How Do I Know What Cell Type I Have?

A biopsy is the only definitive way to confirm a mesothelioma diagnosis and will help your doctor determine what cell type you have, so she can plan the best course of treatment.

Mesothelioma histology requires the study of cancerous mesothelial cells. Your doctor will consult with a histopathologist (i.e., a doctor specializing in the study of diseased cells). They will examine the sample of diseased tissue from the biopsy, analyzing the cell structure to determine the type of cells present in the tumor. This information is critical for doctors when crafting a specialized treatment plan.

A histopathologist uses an additional set of diagnostic tests, called immunohistochemistry, or IHC, to diagnose a patient’s mesothelioma cell type. IHC uses antibodies or matching molecules that attach to different cell markers, which are proteins that classify and identify cells. Specific enzymes are then added to the section of diseased tissue to produce different colors. These color changes help doctors further visualize and identify various tissue abnormalities, and can lead to a more precise diagnosis.

Vijayalaksmhi Ananthanarayanan, MD, a surgical pathologist at Loyola University Medical Center, specializes in diagnosing patients with mesothelioma. She looks at different cell sites to stage the disease and determine how far it has spread and uses that information to confirm or disagree with the original diagnosis. 

Although a biopsy is necessary to confirm mesothelioma, it’s not always a foolproof method.

“There’s always a question of sampling error,” Ananthanarayanan told Mesothelioma Hub. “While it looks like epithelioid mesothelioma in a biopsy, you could end up falling in a section where it could be biphasic or even sarcomatoid. We are not always able to call mesothelioma in a biopsy and despite the biopsy being a gold standard, you can still have the sampling errors, where what has been sampled is not representative of the actual lesion.”

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Benign Tumors of the Mesothelium

In rare cases, mesothelioma tumors may be considered “benign,” even after prolonged asbestos exposure. These masses tend to spread slower than malignant mesothelioma tumors. Due to its rarity, doctors and researchers still do not fully understand the benign form. However, if you are diagnosed with benign mesothelioma, you should still seek treatment as soon as possible to have the tumor(s) removed.