Malignant Sarcomatoid Mesothelioma

In histological terms, there are three different types of mesothelioma: sarcomatoid, epithelial and biphasic. Please see Epithelial and Biphasic for information on these other types of malignant mesothelioma cells. In clinical medicine, the term histopathology refers to the microscopic examination of cellular tissue to gain insight into the manifestations of various diseases.

The type of mesothelioma a patient is diagnosed with can sometimes affect their treatment options. Asbestos.com offers an informational packet with treatment options tailored to your specific diagnosis. To receive your custom packet, please click here.

Malignant sarcomatoid mesothelioma is the least common of the three cellular mesothelioma types. This form of mesothelioma accounts for approximately 7 to 20 percent of cases. When viewed under a microscope, malignant sarcomatoid mesothelioma cells appear as elongated spindle-shaped cells that are irregularly shaped and often overlap one another.

Desmoplastic mesothelioma is considered a variant of sarcomatoid mesothelioma. This form is likely the most difficult of all mesotheliomas to diagnose. When desmoplastic mesothelioma invades or metastasizes, the cells can appear very bland and can be misdiagnosed as benign fibrous tissue. Medical experts in mesothelioma say this form of mesothelioma should not be diagnosed with a needle core biopsy.

It's important to know that malignant sarcomatoid mesothelioma is sometimes difficult to diagnose on the basis of histological methods. For example, cells of another type of cancer called pulmonary sarcomatoid carcinoma are very similar in appearance (as well as other characteristics) to malignant sarcomatoid mesothelioma.

For this reason, if you are diagnosed with cancer and you know that you have been exposed to asbestos at some time in the past, obtaining a second diagnostic opinion may be important. Different types of cancer vary widely in terms of prognosis and treatment options, and if misdiagnosed, patients may not receive the most appropriate treatment for their cancer. Working with a top doctor is often a top priority for mesothelioma patients and we provide a comprehensive packet featuring information on cancer centers and the country’s top doctors.

Sarcomatoid Mesothelioma Prognosis and Treatments

Each of the three cellular forms of mesothelioma may be generally treated in the same way. Treatment is not completely based on the specific type of cells involved, but more so on the location of tumors and the stage of the cancer. Please see Mesothelioma Treatment for more information about treatment options.

Each type of cancer responds to treatment very differently. In general, patients with malignant sarcomatoid mesothelioma have a poorer prognosis than patients with epithelioid mesothelioma, as sarcomatoid cancers are more aggressive and more resistant to treatment. As such, some patients may opt to take a more aggressive treatment approach if they are diagnosed with a variation that is more resistant to treatment. Unfortunately, the general prognosis for all types of mesothelioma is usually poor, and the difference in prognosis between sarcomatoid, epithelioid, biphasic and desmoplastic cancers may amount to as little as a few months.

Sarcomatoid Mesothelioma Biopsies and Histopathology

Patients who undergo medical evaluation to determine if they have malignant mesothelioma will undergo a variety of medical tests that determine the location and nature of the cancer. One of these is a biopsy of cells that are suspected to be cancer cells. During a biopsy samples of suspected cancer cells are removed from several different locations in the tumor site. These cell samples are then evaluated in a laboratory to determine what type of cells they are and whether the cells are malignant. For more information about biopsy procedures a mesothelioma patient might undergo, please see Mesothelioma Surgery - Biopsy .

In the laboratory, cells that are suspected to be cancerous are tested under the principles of histopathology in two ways. First, they are viewed under a microscope to determine their general appearance. Second, they are tested for the presence of oncoproteins and other molecules that are produced by specific types of cancer cells.

When viewed under a microscope, mesothelioma cells and other types of cancer cells can be distinguished from normal healthy cells because of their shape and other differences in appearance. Further tests are needed to determine the exact nature of the cells. These tests evaluate the types of proteins that are present on the surface of the cells.

When mesothelial cells become malignant, they begin to produce different types of proteins and some of these are present on the surface of the cells. Examining the types of surface proteins allows a histologist to determine if the cells are malignant mesothelioma, another type of cancer, or healthy cells. The application of histochemistry in the diagnosis of mesotheliomas is primarily to differentiate epithelial mesotheliomas from mucin-producing adenocarcinoma.

Immunohistochemistry

Though immunohistochemistry is most useful in distinguishing epithelial mesothelioma from other types of epithelial tumors, immunohistochemistry can be used to diagnose sarcomatoid mesotheliomas. Immunohistochemistry involves the localization of proteins or antigens (a substance that starts the generation of antibodies and thus immune system response) in human tissue with help from markers such as enzymes, fluorescent dye or colloidal gold.

The medical process gets its name from the roots “immune,” referring to antibodies used in the procedure, and “histo,” referencing tissue that is chemically analyzed. Extreme detail and caution is used when interpreting immunohistochemical markers and medical professionals typically perform a number of tests in addition to immunohistochemical tests to determine if a tumor is mesothelioma or another type of tumor.

Categorization of Mesothelioma

Cancer specialists use a variety of different methods to categorize malignant mesothelioma. The most well-known method is categorization of the cancer according to its point of origin in the body. For example, pleural mesothelioma develops in the lining of the lungs, pericardial mesothelioma develops in the lining of the heart, and peritoneal mesothelioma develops in the lining of the abdominal cavity. For more information about the different types of mesothelioma, please see Mesothelioma Overview .

Malignant mesothelioma and other types of cancer are also categorized according to how far advanced each case of cancer is, in terms of factors such as the size of tumor(s), and whether the cancer has spread to lymph nodes or other locations. To read more about how cancers are categorized in this way, please see Mesothelioma Staging Systems - Overview.

In addition, malignant mesothelioma and other asbestos cancers are categorized according to the size, shape, and general appearance of cells when viewed under a microscope, as well as the types of proteins that can be detected on the surface of the cells. This type of categorization is called histology, or histopathology.

Each of these systems of categorization provides mesothelioma specialists with important information that is used to determine the exact type of cancer cells they are dealing with in a given case. This information is then used to determine how to treat each patient on an individual basis.

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