Pleural mesothelioma occurs as one of three types of cancer cells: Epithelioid, sarcomatoid or biphasic, which is a combination of both. Determining the mesothelioma cell type helps the doctor design the most effective treatment plan for each patient.

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Last Updated on August 16, 2019.

What Are the Types of Pleural Mesothelioma Cells?

Pleural mesothelioma cells arise from epithelial tissue. When epithelial cells become cancerous, they can develop into epithelioid or sarcomatoid cells, or a combination of the two, known as biphasic mesothelioma.

The main cell types of pleural mesothelioma are:

Epithelioid mesothelioma cells
Epithelioid

Cells are square-shaped with visible nuclei, and they tend to lump together. They are the most common type of cancerous mesothelioma cell, accounting for 50 to 70 percent of all mesothelioma cancers. Because they are the most treatable cell type, patients with epithelial cells have the most favorable prognosis.

Sarcomatoid mesothelioma cells
Sarcomatoid

Cells appear spindle-shaped with plump, elongated nuclei and generally overlap one another. This cellular pattern is seen in about 10 to 20 percent of all mesothelioma tumors. Because they are the most aggressive cells, there are fewer treatment options for patients with this pleural mesothelioma cell type.

Biphasic mesothelioma cells
Biphasic

They are a mixture of epithelial and sarcomatoid cells. Approximately 20 to 35 percent of all mesothelioma tumors are biphasic cell type. Prognosis may vary depending on the mixture of cells, and is more favorable in cases that contain more epithelial cells than sarcomatoid cells. If the tumor contains mostly sarcomatoid cells the cancer is likely to be more aggressive.

Histology of Pleural Mesothelioma Cells

Histology is the microscopic study and examination of tissue appearance, organization and function.

In addition to determining pleural mesothelioma cell type, American Society of Clinical Oncology 2018 pleural mesothelioma treatment guidelines recommend cancer biopsy samples be examined with a type of histology test called immunohistochemistry.

Your doctors can learn more about your cancer and ensure the diagnosis is accurate with immunohistochemistry tests. This will identify the presence and absence of cell markers to confirm the mesothelioma diagnosis and rule out other diseases.

These additional histology lab tests are important for confirming the pathologist’s original determination of the cell type of each patient’s mesothelioma.

An accurate mesothelioma diagnosis is important because it helps your doctor determine the best treatment option and provide an assessment of your life expectancy.

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Why Is Mesothelioma Cell Type So Important?

Determining each patient’s pleural mesothelioma cell type is important for minimizing the risk of mesothelioma misdiagnosis.

For example, misdiagnosis of sarcomatoid cells can happen because these cells closely resemble other conditions, such as localized fibrous tumors, metastasized renal cell carcinoma, fibrosarcoma, fibrous pleurisy, malignant fibrous histiocytoma, adenocarcinoma and pleural liposarcoma.

Also, the type of mesothelioma treatment your cancer doctor plans for you may vary based on mesothelioma cell type.

Treatment Based on Cell Type

Another reason identifying the cell type is important is because each cellular pattern can affect the recommended treatment plan. Cells respond differently to treatment. This is why histology, or the study of cell anatomy, plays a vital role in developing the most effective treatment plan for patients.

Reaction to Treatment by Cell Type

  • Epithelioid cells tend to respond best to treatment, which often leads to a better prognosis.
  • Sarcomatoid cells, on the other hand, don’t respond as well to treatment, which can limit treatment options and lower survival rates.
  • Biphasic cells vary based on the mix of epithelioid and sarcomatoid cells. The more epithelioid cells, the more likely the tumor is to respond to treatment.

The type of cell present in each case can account for up to a 200-day difference in life expectancy.

A team of mesothelioma specialists will determine the prognosis and the best course of treatment based on what cell type is present, location, stage of the cancer and overall health of the patient. A more aggressive treatment plan may be available for epithelioid cases.

If you have a history of asbestos exposure and receive a diagnosis for a cancer or condition other than pleural mesothelioma, you should seek a second opinion. This can ensure the diagnosis is correct and help you receive effective treatment as quickly as possible.