Mesothelioma Cell Types

There are three mesothelioma cell types: epithelioid, sarcomatoid and biphasic. These cellular variations are the result of healthy mesothelial cells mutating due to asbestos exposure.

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Written by Jenna Campagna, RN

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Cell Types of Mesothelioma

A mesothelioma cell can be either epithelioid or sarcomatoid, which accounts for two of the three mesothelioma cell types. These two cells often mix together to form a third cell type, which is called biphasic mesothelioma.

All three mesothelioma cell types can be present in pleural mesothelioma and peritoneal mesothelioma, the two main types of this cancer.

Epithelioid Mesothelioma (Can Occur in Pleural Mesothelioma and Peritoneal Mesothelioma)

epithelioid mobile
  • Clearly defined clump of cells
  • Pink cytoplasm
  • Easier to identify and remove during surgery
  • Cell type with best prognosis

Epithelioid mesothelioma is the most common of the mesothelioma cell types — and also the easiest variation to treat.

It accounts for between 50% and 70% of all mesothelioma cases, according to the American Cancer Society, and is the most treatable. This mesothelioma cell type is a cancerous mutation of epithelial cells.

Epithelioid mesothelioma is the most common cell type for pleural mesothelioma and peritoneal mesothelioma. According to data from numerous sources, this cell type comprises a little more than half of pleural mesothelioma cases and close to 75% of peritoneal mesothelioma diagnoses.

The average life expectancy for this version of pleural mesothelioma is around 19 months, according to a study published on UpToDate in 2018.

A different study distinguished the survival times for each cell type of peritoneal mesothelioma. Epithelioid peritoneal mesothelioma patients had a median survival rate of 55 months.

Sarcomatoid Mesothelioma (Occurs Mainly in Pleural Mesothelioma)

sarcomatoid mobile
  • Overlapping, irregular shape
  • Enlarged, elongated structure
  • Metastasize and spread quickly
  • Most challenging prognosis of the three types of mesothelioma cells

Sarcomatoid mesothelioma is the rarest of the mesothelioma cell types, accounting for between 10% and 20% of all mesothelioma cases.

Sarcomatoid cell type is extremely rare for peritoneal mesothelioma. This cell type comprises around 20% of cases involving pleural mesothelioma.

This cell type has an unfavorable prognosis due to its ability to spread faster than epithelioid cells do. The average prognosis is 8 months for pleural sarcomatoid mesothelioma and 13 months for peritoneal sarcomatoid mesothelioma, according to the aforementioned studies.

Sarcomatoid mesothelioma cells have a histological makeup that resembles sarcoma-type cancers. However, sarcomatoid mesothelioma, like epithelioid mesothelioma, is caused by genetically mutated mesothelial cells. Some epithelial cells will transform into a different type of cell, which become sarcomas when cancerous.

Biphasic Mesothelioma (Can Occur in Pleural Mesothelioma and Peritoneal Mesothelioma)

biphasic mobile
  • Combination of epithelioid and sarcomatoid cell types
  • Prognosis varies depending on which cell is more prevalent
  • Second most common diagnosis for mesothelioma
  • Cells clump together in separate groups

Biphasic mesothelioma is a mixed type of mesothelioma, which has both epithelioid and sarcomatoid cells present.

This type of mesothelioma makes up between 20% and 30% of all cases. A biphasic diagnosis has relatively the same rate of occurrence for both pleural mesothelioma and peritoneal mesothelioma.

It has an average survival time of 13 months, for both pleural mesothelioma and peritoneal mesothelioma, according to the previously cited studies. The prognosis for biphasic mesothelioma depends on the ratio of epithelioid cells to sarcomatoid cells.

If the tumors have more epithelioid cells, then the cancer is likely treatable with surgery. If the tumors have a majority of sarcomatoid cells, then the mesothelioma will likely spread quickly through the body and may be more difficult to treat.

Histology

Histology is the study of your bodily tissue’s cellular makeup. Histology is an important aspect of biology for diagnosing mesothelioma.

When someone is suspected of having mesothelioma, doctors first examine a tissue or fluid sample under a microscope to determine if the cells are cancerous. Samples are typically taken with either a biopsy (tissue) or fluid extraction.

Histopathological testing is the study of diseased tissues. Testing of antibodies and other proteins is used to determine if the cells are mesothelioma. Immunohistochemistry staining, which tests for antibodies and proteins, helps doctors distinguish between the three cell types.

Each of the mesothelioma cell types has a different shape, size and appearance. Experienced mesothelioma specialists can distinguish between epithelioid, sarcomatoid and biphasic cell types. However, further testing is recommended because mesothelioma cells often resemble those of other cancers.

People should be cautious if they were diagnosed with types of cancer which histologically resemble mesothelioma, such as adenocarcinoma. If they were exposed to asbestos in the past, they should seek a second opinion to ensure their diagnosis is correct.

Cellular Makeup

The human body consists of four essential types of tissue: epithelial, connective, muscle and nervous. Each tissue type is comprised of thousands of cells. Epithelial tissue cells can form into mesothelioma; the other three tissue types cannot.

Epithelial Tissues and Mesothelioma

Each type of tissue cell has its own function for the human body. Epithelial tissue lines the body and its cavities, which includes internal organs like the intestines, lungs and heart.

Cancers comprised of epithelial tissue cells, such as mesothelioma, are known as carcinomas. These types of diseases make up most of the known cancers.

The epithelial tissue lining the heart, abdomen and lungs is called the mesothelium. This tissue is permeable, meaning it allows liquids and gasses to pass through it. The mesothelium is comprised of simple-squamous epithelial cells, also called mesothelial cells.

These cells lubricate the mesothelium and protect the nearby body cavities and organs. The wet, permeable construct allows the tissue to bend, which helps the organs expand and contract as needed.

Mesothelial cells also conduct phagocytosis, which is the encapsulation of bacteria, dead cells or foreign particles. This immune response to protect the body involves the absorption of intruder bacteria or dead cells, which the epithelial cells then expel from the body.

However, when asbestos fibers are absorbed by the mesothelial cells, the result is genetic mutation. This phenomenon occurs because the fibers are sharp and the mesothelial cells cannot expel them effectively. The fibers aggravate the cells, which then mutate and duplicate at an unchecked rate. The cellular duplication forms tumors, which is the origin of mesothelioma.

Treatment by Mesothelioma Cell Type

Each histological type of mesothelioma has multiple subtypes, which makes each case unique. However, cell type is not the only factor in a patient’s prognosis and mesothelioma treatment.

Location and stage of the disease are most important in determining treatment for a mesothelioma patient. Doctors are only likely to take cell type into consideration when determining how aggressive treatment should be — as sarcomatoid mesothelioma cells spread rapidly in the body — and this is predicated on the basis of the patient’s overall prognosis.

If you are a mesothelioma patient, you should prioritize finding a specialist who can diagnose and treat your disease. The doctor whom you choose should know of the three cell types and how they distinguish from one another both in microscopic appearance and general prognosis.

Find a mesothelioma specialist who is capable of identifying your cell type, making an accurate diagnosis and forming a treatment plan for your disease. Our free Doctor Match program can connect you with an esteemed specialist.

Last Edited: August 3, 2020.

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