Malignant Mesothelioma Types

Mesothelioma is categorized in two ways, including the location of the cancer (such as pleural versus peritoneal) and the type of tissue or cells involved (the study of which is known as histology). In terms of histology, there are largely three different types of mesothelioma: sarcomatoid, epithelial and biphasic. The term histopathology refers to the study of cell tissue to make a diagnosis of disease or cancer. Pathologists typically study mesothelioma biopsy samples under a microscope to make a cancer diagnosis.

Sarcomatoid Mesothelioma

Sarcomatoid mesothelioma is the least common of the three mesothelioma types, accounting for approximately 7 to 20 percent of cases. When seen under a microscope, these cells are elongated spindle-shaped cells that appear irregular and tend to overlap.

Desmoplastic mesothelioma is a known variant of sarcomatoid mesothelioma and is reportedly the most difficult mesothelioma to diagnose. When this form of mesothelioma spreads, the cells can appear “bland” and have the potential to be misdiagnosed as benign fibrous tissue. Professionals warn that desmoplastic mesothelioma should not be diagnosed using a needle core biopsy sample.

Sarcomatoid mesothelioma can be difficult to diagnose because cells of another type of cancer known as pulmonary sarcomatoid carcinoma can look very similar. Though each type of mesothelioma responds to treatment differently, those diagnosed with sarcomatoid mesothelioma have a poorer prognosis than those with epithelioid mesothelioma. This prognosis is attributed to the fact that sarcomatoid cancers are more aggressive and more resistant to treatment.

If you would like to learn more about sarcomatoid mesothelioma or any of the other types of mesothelioma, please fill out the form on this page to receive a comprehensive packet in the mail detailing treatment options, clinical trials, cancer centers and more.

Epithelial Mesothelioma

The most common type of mesothelioma is epithelial mesothelioma. This cellular variety occurs in approximately 50 to 70 percent of malignant mesothelioma cases. These cells tend to have a well-defined and uniform shape. Epithelial mesothelioma tumors are also referred to as epithelioid mesothelioma.

It should be noted that mesothelial cells, the cells that make up mesothelioma cancer, are actually a type of epithelial cell (which is a common tissue found throughout the body) and are the cells that become cancerous when malignant mesothelioma develops within the pleura, peritoneum or pericardium.

Epithelioid mesothelioma cells closely resemble another type of cancer called adenocarcinoma, which has the potential to develop in the lungs or other vital organs. This type of cancer also originates in epithelial tissue and, when it develops in the lungs, can spread to the mesothelial lining (the pleural membrane). Because of these factors, patients diagnosed with adenocarcinoma who experienced asbestos exposure in the past should seek a second opinion to guarantee accurate diagnosis.

Though prognosis varies from case to case, those with epithelioid mesothelioma typically have a better prognosis than patients with either sarcomatoid or biphasic mesothelioma. This may result in a less aggressive treatment approach depending upon the patient.

Biphasic Mesothelioma

Biphasic mesothelioma, also known as "mixed" mesothelioma, is the second most common type and makes up approximately 20 to 35 percent of mesothelioma cases.

A combination of both epithelial and sarcomatoid cells make up biphasic mesothelioma tumors. The cells are usually found in groups within the tumor, not as an even mix of cells. Because of this factor, several biopsy samples are taken from various locations throughout a tumor to ensure a correct diagnosis.

Because biphasic tumors are more resistant to treatment, patients with biphasic mesothelioma tend to have a poorer prognosis than patients with epithelial or sarcomatoid mesothelioma. As a result, a more aggressive treatment approach is sometimes taken with biphasic mesothelioma with aims of prolonging the life of the patient.

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