SARCOMATOID MESOTHELIOMA

Sarcomatoid mesothelioma accounts for approximately 15% of all mesothelioma diagnoses. It is the least common mesothelioma cell type and the most aggressive form of the disease.

The other two mesothelioma cell types are epithelioid and biphasic. Epithelioid is a distinct type of cell, while biphasic tumors contain a mixture of both epithelioid and sarcomatoid cells. 

Tumors made up of sarcomatoid cells most often grow in the pleura (the lining of the lung) and are less common in the peritoneum (the lining of the abdomen).

Things to Know About Sarcomatoid Mesothelioma

Treatment exists: While patients with a sarcomatoid cell type tend to have a poorer prognosis, there are treatment options available, including promising results with immunotherapy.

Clinical trials may expand options: Patients can seek out clinical trials offering emerging therapies like immunotherapy, which can bring sarcomatoid survival rates closer to the same level as less aggressive forms of mesothelioma

Think about a second opinion: Every now and then, pathologists misdiagnose the severity of mesothelioma. And sometimes a second opinion reveals a better outcome than initially diagnosed. 

There are a few common characteristics of sarcomatoid cells:

• Sarcomatoid cells are long and are shaped like spindles or ovals.
• Sarcomatoid cells grow in a haphazard pattern, which allows them to spread faster than other mesothelioma cell types.
• How sarcomatoid cells spread makes them more resistant to treatment, contributing to a poorer prognosis.

Desmoplastic mesothelioma

Desmoplastic sarcomatoid cells are long and tend to look like bundles of collagen, a healthy protein found in the bones, muscle, tendons, and skin. At least half of a desmoplastic tumor will appear patternless, making it difficult to diagnose. Desmoplastic sarcomatoid cells account for about 5% of all mesothelioma diagnoses.

Lymphohistiocytoid mesothelioma

Lymphohistiocytoid cells are large and shaped like spindles. They usually appear together with immune and inflammatory cells. The lymphohistiocytoid subtype accounts for less than one percent of all mesothelioma diagnoses.

Transitional

Transitional sarcomatoid cells are plump and shaped like spindles.

These tumors are exceedingly rare and can be difficult to diagnose because transitional sarcomatoid cells can resemble epithelioid cells. However, they tend to grow in similar ways to other sarcomatoid subtypes.

Even specialists find it difficult to diagnose sarcomatoid cells due to their similarity to other cancer cells. Sarcomatoid tend to look like the benign tissue cells surrounding the tumor and sarcomas, a form of cancer that occurs in bone, muscle, or cartilage cells.

Diagnosing Through Immunohistochemistry and Biopsy

A pathologist is a doctor who specializes in identifying cells to confirm a diagnosis. Pathologists use a technique called immunohistochemistry to apply special stains to samples taken from a biopsy. This technique helps them differentiate sarcomatoid cells from cells belonging to other cancers.

The stains they use contain markers, often proteins, that are attracted to certain cells. These markers attach themselves to cells, making them easier to see under a microscope. Pathologists can also identify sarcomatoid cells under a microscope by the absence of epithelial, or tissue, elements within the cell.

Sarcomatoid cell types are more resistant to treatment due to their haphazard spread pattern, rigidity, and aggressive metastasis (spread) to other parts of the body.

Surgery is most effective on patients with early stage sarcomatoid mesothelioma because at this stage, the tumor has not yet spread to other parts of the body.

Removing advanced-stage pleural sarcomatoid tumors can be difficult. Sarcomatoid cells tend to spread into the chest wall, making surgery challenging at later stages. 

Sarcomatoid tumors in the abdomen are also difficult to remove due to their proximity to the soft organs in the abdominal area.

Chemotherapy alone has not yet proven itself as an effective treatment for sarcomatoid type mesothelioma.

Radiation therapy may sometimes be used to treat sarcomatoid mesothelioma, especially if cancer is found at an early stage. It may also be used as a palliative treatment to shrink tumors and improve quality of life.

Studies have shown that select drugs have produced positive results when used to treat patients with sarcomatoid mesothelioma: