Sarcomatoid Mesothelioma
Page Medically Reviewed and Edited by Pinar Kanlikilicer, PhD This page has been fact checked by a PhD who specializes in cancer research. Sources of information are listed at the bottom of the article.
We make every attempt to keep our information accurate and up-to-date.
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Just 10% to 20% of mesothelioma cases are sarcomatoid.[1] Sarcomatoid mesothelioma is more aggressive and spreads more readily than the epithelioid type.[2] Treating this type of mesothelioma is more difficult and life expectancy is a year or less.
What Are Sarcomatoid Cells?
Any type of cancer that arises from cells of the mesenchyme tissue type is called a sarcoma. The cells of sarcomatoid cancer are part of tissues from the:
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- Circulatory system
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Sarcomatoid cells of mesothelioma tumors have certain characteristics that distinguish them from epithelial cells:[4]
- They are shaped like tiny spindles with elongated and enlarged nuclei.
- Some cells may even have more than one nucleus.
- These cells are less firmly attached to each other than epithelial cells and are more likely to spread to other areas of the body.
Sarcomatoid Mesothelioma Cells (by WebPathology)
Sarcomatoid Mesothelioma and Subtypes
When the majority of cells in mesothelioma tumors are sarcomatoid, the diagnosis is sarcomatoid mesothelioma. This is the rarest cell type for mesothelioma but the most aggressive.
There are also several subtypes of sarcomatoid cells that may be seen in this type of mesothelioma:[5][6][7][8]
- Desmoplastic cells are bland in appearance without many distinguishing characteristics. This subtype is very difficult to diagnose. This type of growth can be mistaken for a benign condition when in reality, it is characteristic of mesothelioma tumor growth into fibrous tissues.
- Lymphohistiocytoid cells are large and very rare, accounting for just 1% of all mesothelioma diagnoses.
- Heterologous mesothelioma occurs when there are other cell types present in addition to the original mesothelial cells. For example, tumors may contain bone cells in addition to mesothelial cells.
- Rhabdomyoblastic Differentiation is an extremely rare sub-type of sarcomatoid mesothelioma, rhabdomyoblastic differentiation contains a specific type of muscle cell, known as a rhabdomyoblast. Rhabdomyoblasts are early muscle cells that develop into full skeletal muscle tissue.
How Is Sarcomatoid Mesothelioma Diagnosed?
To diagnose any type of mesothelioma:
- The first step is a basic physical examination.
- The physical exam is typically followed by an imaging scan: a chest X-ray, CT scan, or MRI.[9]
- If imaging scans show abnormal tissues that could be potential tumors, the next diagnostic step is a biopsy. During a biopsy, a thin needle is inserted to obtain a fluid or tissue sample.
- Fluid samples rarely show sarcomatoid cells, so for a full diagnosis a tissue sample is necessary.[5]
- A pathologist examines the cells to determine if the tissue is cancer and if it is mesothelioma. At this point, the pathologist will also determine if the cancer is epithelial, sarcomatoid, or biphasic.
Sarcomatoid mesothelioma is easy to misdiagnose as a number of fibrous conditions, both cancerous and noncancerous. These conditions include localized fibrous tumors, pleural liposarcoma, renal cell carcinoma, fibrous histiocytoma, and fibrous pleurisy.[10]
Using Immunohistochemistry in Diagnosis
Immunohistochemistry is a more precise strategy for identifying cell types and diagnosing mesothelioma sub-types. This technique uses diagnostic markers that are specific to cell type to stain tissue. The markers are antigens and antibodies, proteins used by the immune system to identify and target pathogens.[8] It provides a more accurate way to diagnose cell types.
How Is Sarcomatoid Mesothelioma Treated?
Unlike epithelial and biphasic mesothelioma, most specialists do not classify this type of mesothelioma as resectable. This means that sarcomatoid mesothelioma cannot be treated surgically.[5] The cancer spreads too quickly for surgery to be able to remove tumors in their entirety. Sarcomatoid mesothelioma tumors tend to grow into the chest wall, making removal difficult and risky.
Without surgery as a treatment option, specialists must rely on other strategies. Chemotherapy is the most commonly used treatment for sarcomatoid mesothelioma; although, it is not often successful.
A systematic review of thirty sarcomatoid malignant pleural mesothelioma trials showed that there are fewer responses in patients with sarcomatoid histology than in the other mesothelioma sub-types.[11]
Much of the treatment used for sarcomatoid mesothelioma is used to extend the lifespan and make the patient comfortable. Chemotherapy and radiation can shrink tumors, which may help a patient live longer. Shrinking tumors can also help reduce symptoms.
What Is the Outlook for Sarcomatoid Mesothelioma?
Prognosis varies depending on individual factors such as the stage of the cancer, the age of the patient, lifestyle habits, and overall health. Overall, the prognosis for sarcomatoid mesothelioma is generally poor.
Studies indicate that a diagnosis of sarcomatoid mesothelioma, even with surgical treatment, results in a median survival time of just four months.[5] Chemotherapy and radiation therapy may extend life expectancy better than surgery, but they have minimal effect.
If you have symptoms of mesothelioma, or have been exposed to asbestos, early and accurate diagnosis is crucial for receiving the best possible prognosis. The earlier you receive a diagnosis and start treatment, the better your life expectancy and comfort level will be.
Page Medically Reviewed and Edited by Pinar Kanlikilicer, PhD
Dr. Pinar Kanlikilicer has a PhD in Biomedical Engineering. She completed her 5-years of postdoctoral training in the Department of Experimental Therapeutics at MD Anderson Cancer Center. She is currently working in the field of cancer as a research scientist.