Under the microscope, mesothelioma is classified into three cell types. The cell type is one of the most important factors in determining treatment options and prognosis, so it is always identified during biopsy.
Epithelioid Mesothelioma
The most common cell type, accounting for roughly 50-70% of cases. Epithelioid cells are more uniform and tend to cluster together, which makes the cancer less aggressive and more responsive to treatment than the other types. Patients with epithelioid mesothelioma generally have the most favorable prognosis and the widest range of treatment options, including surgery for eligible patients.
Sarcomatoid Mesothelioma
The least common and most aggressive cell type, making up about 10-20% of cases. Sarcomatoid cells are spindle-shaped and spread more readily, and the cancer tends to resist chemotherapy and radiation more than the epithelioid type. This gives it the most guarded prognosis, and patients are less often candidates for aggressive surgery. Sarcomatoid disease can be harder to diagnose because its cells can resemble other cancers.
Biphasic Mesothelioma
A mixture of both epithelioid and sarcomatoid cells, accounting for roughly 20-35% of cases. Prognosis and treatment response depend on the proportion of each cell type — tumors with a higher percentage of epithelioid cells tend to behave more like epithelioid mesothelioma and respond better, while those dominated by sarcomatoid cells behave more aggressively.
Why Cell Type Matters
Because cell type strongly influences how the cancer responds to surgery, chemotherapy, radiation, and immunotherapy, an accurate pathology diagnosis is essential to treatment planning. Determining cell type sometimes requires specialized testing (immunohistochemistry) and, in difficult cases, a second pathology opinion.
See also the stages guide and life expectancy and prognosis.
If you were diagnosed with any type of mesothelioma and were exposed to asbestos at work, in the military, or in a building, you may be entitled to significant compensation through asbestos trust funds and civil litigation.
This information is educational, drawn from sources such as the American Cancer Society and National Cancer Institute, and is not medical advice. Consult your own physician about your diagnosis.