Support for Patients, Family Members, and Caregivers
Text Size:

Mesothelioma Histology (Cell Types)

In addition to classifying mesothelioma by location, the disease is further classified by cell type, which is scientifically known as histology. Cell type describes the cell’s appearance and its actions.

There are 300 different types of cells in the body, which includes glands, hair follicles and photoreceptors in the eye. In the case of mesothelioma cell types, there are three main types of cells that are cancerous. While cell type does not dramatically change the mesothelioma treatment protocols, it gives physicians a better picture of the overall prognosis.


These cells are uniform in shape with an elongated pattern. They are easy to distinguish under a microscope.

  • Epithelial cells account for up to 70 percent of all mesothelioma diagnoses.
  • Epithelial tumors respond better to treatment, including surgery, than tumors made of other cell types. This is a leading determination of a successful outcome.
  • Epithelial is an umbrella category for more than a dozen other mesothelioma subtypes, including Well Differentiated Papillary Mesothelioma.


These cell shapes are elongated, spindle-shaped and form in masses that protrude. Under the microscope, this cell type looks disorganized and haphazard. This cell type produces aggressive tumors.

  • Sarcomatoid cells account for up to 20 percent of mesothelioma cases but the least common type of cell.
  • It is also called diffuse malignant fibrous, sarcomatous and spindled mesothelioma.
  • Sarcomatoid tumors usually develop in the pleura. Up to 20 percent of all cases of pleural mesothelioma include sarcomatoid tumors.
  • Sarcomatoid tumors are known to look like other, less dangerous cell types and tumors, making them difficult to diagnose. Because of this, sarcomatoid tumors can be very dangerous.


These cell types are a mixture of epithelial and sarcomatoid. They lack a specific shape. This cell type is difficult to detect because of its mixed appearance.

  • With up to 35 percent of all cases having biphasic cells, this is the second most common cell type.
  • Biphasic cells are more commonly seen in cases of pleural mesothelioma.
  • Life expectancy rates for those with biphasic cells vary because of varied cell types. Some treatments and clinical trials are aimed at targeting specific cell types.
  • Biphasic cells are difficult to detect because the cell type may not exist in needle biopsies, not giving researchers a clear view of the problematic cell type. Larger tissue samples, through a surgical biopsy, are typically needed for a clearer diagnosis.

Well Differentiated Papillary Mesothelioma (WDPM)

This usually develops in the peritoneum. It is far less aggressive and is mostly seen in women. Because of its slow growth, this cancer typically does not spread, or metastasize.

Although some physicians say WDPM tumors are relatively benign, they require medical intervention. No effective treatment has been established because this cancer is so rare.


  1. Inai, Kouki. “Pathology of Mesothlioma. National Institute of Health. 2008. Retrieved from
  2. Husain, Aliya, et al. “Guidelines for Pathologic Diagnosis of Malignant Mesothelioma.” International Mesothelioma Interest Group. 2009. Retrieved from
  3. National Cancer Institute at the National Institutes of Health. Cellular Classification of Malignant Mesothelioma. Retrieved from
Free Assistance With
VA Claims & Other Benefits
Are you a veteran diagnosed with mesothelioma? We have qualified veterans on staff who are standing by to assist you with VA related claims and other potential benefits.
Contact Me