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Biphasic Mesothelioma

Approximately 20 percent of diagnosed mesotheliomas are biphasic. This is one of three major ways of classifying mesothelioma by cell type. Cells in mesothelioma tumors may be epithelioid, sarcomatoid, or a mix of the two, known as biphasic. There are a few other rare cell types and several subtypes, but these three account for nearly 100 percent of diagnoses.

The treatment and prognosis for biphasic mesothelioma varies by individual. The more sarcomatoid cells there are, the more aggressive the treatment will need to be and the worse the prognosis. With more epithelial cells the tumor will be easier to treat, although still challenging, and the prognosis slightly better. A complete diagnosis is necessary, not just to determine a tumor is mesothelioma, but also to determine cell type so that the right treatment plan can be made and put into action.

Histological Classification

Histology is the microscopic study of cells. When a tumor is found, usually through imaging scans, the next step in diagnosing it is to take a biopsy. The cells removed in the biopsy sample can then be examined by a pathologist to determine whether they are benign or malignant, and from which type of tissue they originated. This may include the peritoneum, the pleura, the pericardium, or even somewhere else in the body if the cancer originated elsewhere an metastasized to the mesothelium.

Once a diagnosis of mesothelioma has reached this stage, the pathologist will also look at the biopsied cells to determine their histological classification, or cell type. This is when the diagnosis includes the category of epithelioid, sarcomatoid, or biphasic. To be classified as biphasic the biopsied sample must be made up of more than ten percent of either epithelioid or sarcomatoid cells with the rest made up of the other type.

Sarcomatoid and Epithelioid Cells

Biphasic mesotheliomas are tumors that include a mix of these two cell types. Epithelial cells make up tissue in the body that lines the surfaces of organs, blood vessels, and the interiors of cavities. When these cells become cancerous, or malignant, the type of cancer is called a carcinoma. A sarcoma on the other hand arises from cells that make up bone, fat, muscle, vascular, and connective tissue. Sarcomas are much rarer than carcinomas.

Epithelioid mesothelioma cells are easier to treat and are less aggressive because they tend to stick together. Sarcomatoid cells, on the other hand, adhere less to each other and are more likely to spread quickly to other organs. This makes the sarcomatoid type of mesothelioma more difficult to treat. Epithelioid type cells appear as rounded, cube-like shapes, while sarcomatoid cells are spindle shaped and more disorganized in arrangement. Biphasic tumors could have up to 90 percent of either type of cell.


The diagnosis of biphasic mesothelioma is like the diagnosis of any type of mesothelioma. It usually begins when a patient experiences symptoms and goes to the doctor. After a medical history and physical exam the doctor may scan the patient to create an image of the interior of the body. An X-ray, CT scan, MRI, or PET scan, or two of the above, may be used to determine if there is any abnormal tissue or potential tumors.

If a scan does show something abnormal, the next step is to biopsy that tissue. In most cases this only requires the insertion of a needle to withdraw fluid or a small amount of tissue. If the tumor is particularly hard to reach, a more invasive biopsy may be necessary, involving an incision or surgery.

With biopsied tissue or fluid, a pathologist can examine the cells of the tumor. Looking under a microscope with the sample stained this professional can try to determine if the cells are malignant or benign, and whether they originated in the mesothelium or some other tissue. This histological diagnosis is not always accurate and especially with mesothelioma it can be tricky to distinguish cells from other types of cancer.

If the pathologist makes a confident diagnosis of mesothelioma, he or she will then look at the cells to determine what type they are. If there is a mix of epithelioid and sarcomatoid cells in the sample the diagnosis will be biphasic mesothelioma.


The treatment for biphasic mesothelioma depends on many factors. One of these is the ratio of epithelial to sarcomatoid cells. If there are more epithelial cells the cancer is likely to spread more slowly and mostly to areas near the original tumor. If sarcomatoid cells dominate the tumor it is more likely to be a fast-growing, aggressive cancer and more distant metastasizing is possible.

There are also individual factors to consider such as the patient’s health, where the tumor is located, and how much metastasis has occurred. Surgery is usually only performed for epithelioid mesotheliomas, but if the biphasic tumor is mostly epithelioid, surgical removal of the tumor or part of it may be part of treatment, followed by radiation and chemotherapy. For mostly sarcomatoid biphasic tumors, chemotherapy and radiation are more likely choices for treatment.


As with treatment, prognosis varies for patients with biphasic mesothelioma. Unfortunately the prognosis generally, for any type of malignant mesothelioma, is not good. Even with mostly epithelial cells, this type of cancer is aggressive, tends to spread quickly, and is often not diagnosed until it is in the latter stages of development. Survival rates for biphasic mesothelioma are not good, but these patients are expected to live longer than those with true sarcomatoid tumors. The more epithelial cells there are, the longer a patient will live in most cases.

All types of malignant mesothelioma have a strong correlation with regular asbestos exposure. If you were exposed at work for many years and then received a diagnosis of biphasic mesothelioma, you may feel that someone else is to blame. Either your employer or the maker of asbestos-containing materials could be blamed for your current diagnosis and suffering. You can take advantage of asbestos and mesothelioma trust funds or start a lawsuit if you feel you have a strong case to make.

Page edited by Dave Foster

Dave has been a mesothelioma Patient Advocate for over 10 years. He consistently attends all major national and international mesothelioma meetings. In doing so, he is able to stay on top of the latest treatments, clinical trials, and research results. He also personally meets with mesothelioma patients and their families and connects them with the best medical specialists and legal representatives available.

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