This type of mesothelioma is much less common when compared to epithelioid cell mesothelioma. It can occur in the lungs, the heart, and the abdomen, located where the linings of these areas become cancerous.
Understanding Sarcomatoid Mesothelioma
Sarcomatoid mesothelioma accounts for about 10-15 percent of all mesothelioma types. It is associated with a poorer prognosis than in the case of epithelioid mesothelioma.
Pathology of Sarcomatoid Mesothelioma
In this type of mesothelioma, the normal, cube-shaped cells seen in epithelioid mesothelioma become more random and irregular in shape. The cells are large, elongated and spindle-shaped, which give them the nickname “spindled mesothelioma.” They can be found as the sole type of cells in mesothelioma or part of biphasic mesothelioma, which is a mixture of epithelioid and sarcomatoid cells. There is another type of sarcomatoid mesothelioma that can show up under the microscope. This type, called desoplastic mesothelioma, often resembles normal cell types under the microscope. This can make it difficult to diagnose, especially when no other cancerous cell types are nearby.
Immunohistochemistry is sometimes used to identify the difference between normal tissue and sarcomatoid mesothelioma. This is when special stains are used on the microscope slide after antibodies to proteins on sarcomatoid mesothelioma cells are mixed with the cancer cells. The antibodies themselves are stained so that they will show up under the microscope if it is sarcomatoid mesothelioma.
Signs and Symptoms of Sarcomatoid Mesothelioma
The main signs and symptoms that would lead a doctor to suspect mesothelioma include a history of asbestos exposure and these symptoms:
- Shortness of breath from fluid on the lungs or abdomen
- Excess fluid in the abdomen or around the lungs which can contain cancer cells.
- Unexplained weight loss or fevers
- Chest or abdominal pain
Diagnosing Sarcomatoid Mesothelioma
After the doctor becomes suspicious of cancer, X-rays can be taken to look for thickening of the pleura, enlarged lymph nodes and fluid around the lung, abdomen, or heart. Often further testing is required, such as a CT scan of the chest/abdomen, an MRI scan of the chest/abdomen or a PET scan of the chest or abdomen.
A PET scan shows areas of increased uptake of radioactive glucose by hyper-metabolizing cells. Sarcomatoid mesothelioma cells divide rapidly and have a higher rate of metabolism than normal tissue so that these areas are highlighted on the PET scan.
Biopsies of sarcomatoid mesothelioma can be very difficult. It is difficult to tell different sarcoma-like cancers from one another and a core biopsy may not look much different than scar tissue under the microscope. Special testing may need to be done in order to finally reach a diagnosis.
Treatment of Sarcomatoid Mesothelioma
The treatment of any type of mesothelioma depends on the cancer stage and on the cell type. The mainstays of therapy for mesothelioma are surgery, chemotherapy and radiation. Howver, not all patients receive every type of mesothelioma treatment because the cancer has often metastasized at the time of discovery, making surgery less effective. Palliative surgery, which is surgery that addresses symptoms and is designed to make you more comfortable, is most done in stage 3 and stage 4.
Some chemotherapy regimens used for the disease include doxorubicin plus selenite and a combination of Adriamycin, dacarbazine, vincristine, and cyclophosphamide. Because surgery is often difficult to do with this kind of tumor, chemotherapy is the next best option.
Radiation is reserved for areas of cancer that are clustered in one spot. Radiation therapy can reduce symptoms but cannot cure the disease.
Prognosis of Sarcomatoid Mesothelioma
Many cases of sarcomatoid mesothelioma are resistant to even the best forms of treatment. This means that the prognosis is poorer in these patients. The average mesothelioma survival rate is around seven months from the time of diagnosis.