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Karen Ritter, RN BSN
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Important Facts About Sarcomatoid Mesothelioma
- Sarcomatoid mesothelioma is the rarest mesothelioma diagnosis and has the poorest life expectancy.
- Sarcomatoid cells are mutated epithelial cells caused by irritation from asbestos exposure.
- Due to the rapid growth and spread of sarcomatoid cells, this cell type is often difficult to treat.
What Is Sarcomatoid Malignant Mesothelioma?
Sarcomatoid Cell Type
Sarcomatoid mesothelioma is a rare subtype of malignant mesothelioma, which results from mutated mesothelial cells. Specialists evaluate the cells present in the patient’s body to diagnose the mesothelioma type, which can be primarily sarcomatoid, primarily epithelioid, or a combination of the two (called “biphasic”).
Asbestos exposure – the only cause of mesothelioma – leads to irritation of healthy mesothelial cells, which then results in genetic mutation and mesothelioma tumor formation. Once toxic asbestos fibers infiltrate the body, the microscopic particles can become lodged in the mesothelium, which is a thin lining surrounding the lungs, abdomen and heart.
The mesothelium is composed of healthy epithelial cells, and irritation to these healthy cells causes them to mutate into sarcomatoid cells or other mesothelioma tumors.
According to a report in Modern Pathology, sarcomatoid mesothelioma tumors form far more often in the pleura than it does in the peritoneum. A study showed that 98% of sarcomatoid cases are pleural mesothelioma.
This cell type of mesothelioma metastasizes at a rapid pace, meaning tumors spread quickly to surrounding tissues and other parts of the body. Sarcomatoid mesothelioma is the most difficult cell type to treat due to the aggressive nature of this disease, although developing treatments (such as immunotherapy) are leading to improved survival.
Characteristics of Sarcomatoid Mesothelioma Cells
What Causes Sarcomatoid Mesothelioma?
Sarcomatoid cells were once healthy epithelial cells. Asbestos exposure and irritation to the healthy cells cause them to mutate into cancerous tumors.
The human body is made up of four types of cells: epithelial cells, nerve cells, muscle cells and connective tissue cells. Epithelial cells are found in the linings of the lungs, abdomen and heart. The lining of these organs is called the mesothelium.
When asbestos fibers invade these linings, they stick to the mesothelium and irritate the healthy mesothelial cells, causing genetic mutation and tumor formation. This is how mesothelioma forms. The epithelial cells affected by asbestos exposure can transform into sarcomatoid cells.
Epithelial cells line the thin membrane just outside of the lung cavity, abdominal cavity and heart.
Epithelial cells can transform into sarcomatoid cells when they become cancerous. This change is called the epithelial-to-mesenchymal transition (EMT).
Mesenchymal cells are usually part of the body’s connective tissue (such as bones and cartilage). When they become cancerous, they are called "sarcomas."
Sarcomatoid Mesothelioma Symptoms
Symptoms vary depending on where the cancer forms, such as in the lining of the lungs or in the lining of the abdominal cavity. Mesothelioma symptoms can resemble those caused by other illnesses, which is why early detection is often difficult.
Sarcomatoid pleural mesothelioma symptoms include:
- Shortness of breath
- Chest or back pain
- Difficulty swallowing
- Pleural effusions (fluid buildup)
Sarcomatoid peritoneal mesothelioma symptoms include:
- Abdominal pain
- Abdominal distention (from accumulation of fluid in the abdomen)
Sarcomatoid Mesothelioma Diagnosis
The sarcomatoid cell type is often difficult to identify and accurately diagnose. The rare nature of this cell type can leave physicians with a lack of knowledge and experience in providing an accurate diagnosis.
Another challenge in diagnosing sarcomatoid mesothelioma is the similarity between healthy cells and cancerous cells. Sarcomatoid cells can appear similar to benign tissue, which makes it difficult to identify. Due to the infrequency of diagnosing this mesothelioma cell type, doctors are often unfamiliar with the sarcomatoid cell type and the cell appearance.
The sarcomatoid mesothelioma diagnostics process begins with a fluid extraction or tissue biopsy to determine what type of cells are present. In some cases, the concentration of malignant cells in the biopsy may be too low for detection and determining which cells are healthy or cancerous can be challenging.
According to a study published in the National Library of Medicine, sarcomatoid mesothelioma has been shown to have the most inconsistent expression of cytokeratin and calretinin, two common tumor markers. This is one of the obstacles specialists may face during histoimmunochemical testing as they attempt to identify the cell presence and determine a proper diagnosis.
Immunohistochemistry for Sarcomatoid Mesothelioma
If the biopsy is adequate, pathologists will use immunohistochemistry to accurately identify the cell type. Immunohistochemistry involves staining antibodies and using them to check for antigens (markers). The antibodies bind to the antigens and the stain (or dye) will be activated. This identifies the antigen and helps specialists determine the cell type of the patient’s mesothelioma.
Immunohistochemical markers for sarcomatoid mesothelioma include:
- Podoplanin (D2-40)
Many oncologists and surgeons do not have the experience required to understand the complexity of mesothelioma. This cancer is quite rare and requires a deep understanding to identify, diagnose, and treat. Patients diagnosed with mesothelioma, especially those with rare cell types like sarcomatoid, should seek a second opinion from a doctor specializing in mesothelioma.
Mesothelioma specialists dedicate their careers to better understanding mesothelioma and how to effectively treat it. Finding a mesothelioma specialist to analyze diagnostic tests and determine an effective treatment plan can make a difference in having a positive outcome.
Getting a second opinion from a mesothelioma specialist can significantly improve your chances of survival. Oncologists and surgeons do not typically have the experience needed to devise the perfect treatment plan, as some mesothelioma treatment methods are emerging and not yet FDA-approved.
Due to the rarity of mesothelioma, it is sometimes necessary to get a pathology lab to provide a second opinion to obtain a definitive diagnosis. For instance, Johns Hopkins Medicine has a specialized pathology lab dedicated to providing second opinions for diagnostic purposes.
Specialists can confirm the best treatment plan for each individual patient by analyzing pathology reports. Not all cancer is the same, and not all treatments are effective for all patients. Receiving a second opinion from a qualified specialist is crucial in fighting mesothelioma.
Sarcomatoid Mesothelioma Treatment Options
Sarcomatoid mesothelioma is the rarest cell type of mesothelioma but also the most aggressive. Treatment options are often limited as tumors with this mesothelioma cell type have a poor response to typical treatment methods.
Surgery, chemotherapy and immunotherapy are the top treatment options used for mesothelioma. Surgery can be ineffective for patients with the sarcomatoid cell type. The scattered growth pattern of sarcomatoid cells makes removal difficult. These types of cells don’t clump together like epithelioid mesothelioma cells do, which creates strict criteria for surgery eligibility.
Subtypes of Sarcomatoid Mesothelioma
There are three rare subtypes of sarcomatoid mesothelioma. The subtype of the cancer can affect treatment. Certain subtypes are less responsive to traditional treatments and add a layer of complexity to the diagnostic process.
The three subtypes of sarcomatoid mesothelioma are:
- Transitional mesothelioma
- Lymphohistiocytoid mesothelioma
- Desmoplastic mesothelioma
Prognosis for Sarcomatoid Mesothelioma
The average prognosis for sarcomatoid mesothelioma is not as hopeful as the other two cell types. According to a 2018 study published in Clinical Lung Cancer, the median survival rate for patients who do not undergo treatment is less than six months.
If the disease is diagnosed at an early stage, and if the patient meets the surgical and treatment criteria, then their postoperative life expectancy increases to an average of 11.2 months.
The location of the mesothelioma also affects prognosis. Peritoneal mesothelioma often has better survival rates than pleural mesothelioma. In one study:
- Sarcomatoid pleural mesothelioma patients survived for an average of 8 months
- Sarcomatoid peritoneal mesothelioma patients survived for approximately 13 months on average
There are sarcomatoid mesothelioma patients who have significantly outlived their life expectancy. These survival stories are largely thanks to early diagnosis and aggressive treatment.
Learn how survivors beat the odds in our free Mesothelioma Survivor’s Guide.
Support Options for Patients With Sarcomatoid Mesothelioma
Mesothelioma is a devastating disease and can take a toll on a patient’s physical and mental health. It’s important to maintain your health and overall well-being during treatment and recovery from treatment. There are many resources available to patients with mesothelioma, as well as their loved ones and caregivers.
Frequently Asked Questions About Sarcomatoid Mesothelioma
What does sarcomatoid mesothelioma look like?
Sarcomatoid mesothelioma is difficult to identify in tissue staining and under the microscope. The cells don’t possess a defined structure but rather an elongated and inconsistent shape. They also can have multiple nuclei, don’t show any clear borders, and don’t always develop in clear patterns or bunches.
How common is sarcomatoid mesothelioma?
Sarcomatoid mesothelioma is diagnosed in 20-30% of cases. It’s most common in pleural mesothelioma and rarely gets diagnosed in peritoneal mesothelioma. Of the approximately 3,000 new cases each year in the United States, sarcomatoid mesothelioma makes up no more than 1,000 of them.
What is the average survival time for people With sarcomatoid mesothelioma?
Sarcomatoid mesothelioma has the poorest average prognosis of the three cell types. The average life expectancy after diagnosis is eight months. For patients who receive treatment, the prognosis can improve to 1-2 years. However, there are stories of patients with sarcomatoid mesothelioma far surpassing their life expectancy and living for five or more years.
How is sarcomatoid mesothelioma treated?
Treatment is difficult due to the physical properties of this cell type. They don’t clump together and they’re difficult to distinguish from healthy tissue, which makes removal during surgery challenging for doctors. Many cancer centers and clinical studies exclude sarcomatoid mesothelioma patients due to these obstacles, but some studies welcome these patients. Mesothelioma Guide’s team can help you or a loved one find a clinical trial to fit your needs.
Sources & Author
- About Malignant Mesothelioma. American Cancer Society. Retrieved from: https://www.cancer.org/content/dam/CRC/PDF/Public/8733.00.pdf. Accessed: 10/01/19.
- What Is a Soft Tissue Sarcoma? American Cancer Society. Retrieved from: https://www.cancer.org/cancer/soft-tissue-sarcoma/about/soft-tissue-sarcoma.html. Accessed: 04/17/19.
- Malignant Pleural Mesothelioma. Edited by Kenneth O’Byrne and Valerie Rusch. Oxford University Press. 2006.
- Signs and Symptoms of Mesothelioma. American Cancer Society. Retrieved from: https://www.cancer.org/cancer/malignant-mesothelioma/detection-diagnosis-staging/signs-symptoms.html. Accessed: 10/04/19.
- Guidelines for Pathologic Diagnosis of Malignant Mesothelioma. International Mesothelioma Interest Group. Retrieved from: https://www.archivesofpathology.org/doi/pdf/10.5858/arpa.2017-0124-RA. Accessed: 10/04/19.
- EURACAN/IASLC proposals for updating the histologic classification of pleural mesothelioma: towards a more multidisciplinary approach. Journal of Thoracic Oncology. Retrieved from: https://www.jto.org/article/S1556-0864(19)33232-0/pdf. Accessed: 10/11/19.
- Life Expectancy in Pleural and Peritoneal Mesothelioma. Lung Cancer International. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5292397/. Accessed: 10/11/19.
- The basics of epithelial-mesenchymal transition. U.S. National Library of Medicine. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2689101/. Accessed: 04/17/19.
- Survival by Histologic Subtype of Malignant Pleural Mesothelioma and the Impact of Surgical Resection on Overall Survival. Clinical Lung Cancer. Retrieved from: https://www.ncbi.nlm.nih.gov/pubmed/30224273. Accessed: 10/11/19.
- Pleura Mesothelial tumors Mesothelioma – sarcomatoid. Pathology Outlines. Retrieved from: http://www.pathologyoutlines.com/topic/pleuramesotheliomasarcomatoid.html. Accessed: 01/04/19.
- Sarcomatoid mesothelioma: a clinical-pathological correlation of 326 cases. Modern Pathology. Retrieved from: https://www.nature.com/articles/modpathol2009180.pdf. Accessed: 09/04/18.