The Sarcomatoid Pleural Mesothelioma

Sarcomatoid mesothelioma accounts for approximately 7 to 20 percent of all mesothelioma cases diagnosed. The other two subtypes of mesothelioma include epithelial and biphasic, which are more common than sarcomatoid. A variant form of sarcomatoid is desmoplastic mesothelioma. This form of mesothelioma is considered the most difficult one to diagnose because of its similarity to sarcomatoid and the fact that the cells can be misdiagnosed as benign fibrous tissue.

Sarcomatoid mesothelioma cells are usually elongated and spindle-shaped. These cells tend to be irregular in size and often overlap one another. When analyzed under a microscope, sarcomatoid mesothelioma cells may resemble another form of cancer called pulmonary sarcomatoid carcinoma. If you or a loved one has been diagnosed with pulmonary sarcomatoid carcinoma, a second opinion from a qualified physician is recommended to make sure an accurate diagnosis has been made.

Treatment options can differ significantly depending on what form of cancer a patient has been diagnosed with. In the case of sarcomatoid mesothelioma, where prognosis is often very poor, a patient may elect a treatment regimen that is much more aggressive since this form of cancer is typically resistant to treatment. Such options may include surgery, chemotherapy or radiation therapy.

Regardless of the subtype a patient may exhibit, developing pleural mesothelioma is almost exclusively caused by asbestos exposure. Exposure to this naturally occurring substance can occur by either inhaling or ingesting asbestos fibers. In many cases, these fibers have become airborne due to the disturbance of asbestos-containing materials. While complications may not present themselves immediately after someone has been exposed, symptoms of pleural mesothelioma can develop between 20 and 50 years later in life.

Sources
1. www.cancer.org
2. www.cancer.gov
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Sarcomatoid Mesothelioma Survival

who are diagnosed with sarcomatoid mesothelioma face a much poorer outlook than those with the more common epithelioid form of the disease, according to a study published online January 15 in the journal, Modern Pathology. The study also found evidence linking sarcomatoid mesothelioma with higher asbestos exposures, and confirmed that proteins called cytokeratins (CK) are among the most useful markers for diagnosing this type of mesothelioma.

Sarcomatoid mesothelioma is the least common form of this already rare cancer, comprising only about 10 percent of the 2,000 to 3,000 mesothelioma cases diagnosed in the U.S. each year. It is also the most aggressive type of this disease. Studies find that patients with sarcomatoid mesothelioma survive for an average of just five to six months.

That short survival time makes it essential for doctors to diagnose sarcomatoid mesothelioma as quickly as possible. “Accurate diagnosis of mesothelioma is important both for optimal treatment and determining progress,” says study author Victor L. Roggli, MD, Professor of Pathology at Duke University Medical Center. Yet sarcomatoid mesothelioma is among the most difficult forms of the disease to diagnose with any accuracy, because it can look very similar to other non-cancerous and cancerous tumors, including other sarcomas (a cancer that forms in connective tissue). “Some sarcomas that sarcomatoid mesothelioma can be confused with do better in terms of survival,” Dr. Roggli says.

The researchers say that immunohistochemistry—a diagnostic staining technique that looks for protein markers in cells that are specific to certain cancers—is not as useful for sarcomatoid tumors as it is for other types of mesothelioma. “Special stains are of rather limited benefit and if the pathologist relies on staining of the tumor alone, mistakes can be made,” Dr. Roggli says. However, of the immunohistochemical markers available, CK is among the most useful for diagnosing sarcomatoid mesothelioma. “The best approach to diagnosis is close communication between the radiologist looking at the films, the doctor who takes the biopsies (surgeon, radiologist, or pulmonologist), and the pathologist,” he says.

To learn more about this aggressive cancer, Dr. Roggli and his colleagues examined database records taken from 326 patients. They discovered that most of the patients with sarcomatoid mesothelioma had cancer in the chest area (pleura).

Using x-ray analysis, the authors found that patients had more asbestos fibers in their tissue samples compared with patients who had non-sarcomatoid tumors. “Our findings indicate that on average, sarcomatoid mesotheliomas are associated with heavier exposures to asbestos than the other mesothelioma types,” Dr. Roggli says. Most of those fibers were the amosite form of asbestos.

The researchers also confirmed that sarcomatoid mesotheliomas have a particularly dire prognosis compared with other forms of this cancer. In the study, only 30 percent of patients with sarcomatoid mesothelioma were alive at six months, and only 10 percent were alive after a year. By comparison, survival rates for the more common epithelioid mesothelioma are in the range of 12 to 24 months.

“Our study is the largest by far of this relatively rare form of a rare cancer (mesothelioma),” says Dr. Roggli. “Our findings confirm reports by others that this type has a rather grim prognosis, a strong association with asbestos, and location mainly in the chest.”

Sources:
Klebe S, Brownlee NA, Mahar A, Burchette JL, Sporn TA, Vollmer RT, Roggli VL. Sarcomatoid mesothelioma: a clinical-pathologic correlation of 326 cases. Modern Pathology; 2010 Jan 15 [Epub ahead of print].American Cancer Society. What are the Key Statistics About Malignant Mesothelioma?


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Biphasic Mesothelioma Cancer

Approximately 20 percent to 40 percent of the mesothelioma cancer cells fall into the biphasic category, which is combination of the sarcomatoid and epithelioid types. The biphasic type can occur with the two types of cells intermixed continuously throughout the tumor, or with them in specific groupings. Transitional areas between the two cell types are often present. Learn more about biphasic mesothelioma cancer.
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Sarcomatoid Mesothelioma Cancer

Sarcomatoid mesothelioma is the least common type of mesothelioma cancer cell and accounts for approximately 10 percent to 15 percent of malignant mesothelioma. These cells typically have more of an oval, irregular shape and the nucleus of each cell is not as visible with a microscope as the epithelioid mesothelioma cancer cells. Because of the similarity of appearance, the sarcomatoid cancer cells can also easily be confused with the more typical sarcoma cancer cells. Learn more aboutsarcomatoid mesothelioma cancer.

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Epithelioid Mesothelioma Cancer

Epithelioid mesothelioma is the most common cell type, constituting approximately 50 percent to 70 percent of all malignant mesothelioma. These cells are relatively uniform in shape and have a tubular pattern with a distinct cell nucleus. The individual cells are shaped like cubes or multi-sided boxes.
Because of the similarity between adenocarcinoma and mesothelioma cancer cells, they are often confused and mesothelioma can be misdiagnosed. Inspection of the cancer cells under high-powered microscopes and identification of unique characteristics of the chemical properties of the cells can help make the proper diagnosis. Learn more about epithelioid mesothelioma cancer.

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Malignant mesothelioma


Malignant mesothelioma is generally divided into three histological categories, or types of cells: epithelioid, sarcomatoid and biphasic mesothelioma. Within each of these mesothelioma cancer cell types, subtypes exist. Many mesothelioma patients display more than one cell type.

The diagnosis of mesothelioma cannot be specifically by lung x-rays or other types of imaging, because many different types of cancer can be present in the lungs. The images may show that a tumor is present, but do not provide an indication of whether the tumor is mesothelioma. A biopsy must be performed where the mesothelioma cancer cell types are used to distinguish mesothelioma from other types of cancer, such as lung cancer.

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