Mesothelioma

Mesothelioma Cell Types

Malignant mesothelioma is generally divided into three cell type categories: epithelioid, sarcomatoid and biphasic mesothelioma. Many subtypes exist within each of these mesothelioma cell types, and mesothelioma patients often display more than one cell type. These three main cell types differ in aggressiveness, in the way respond to mesothelioma treatment, and the way they appear under a microscope. A mesothelioma patient's cancer cell type is determined through an examination of biopsied tumor tissue by a histopathologist (an expert in the study of diseased tissue). When the histopathologist views the cancer cells under a high-powered electron microscope, he or she can confirm a case of malignant mesothelioma and determine the type and stage of the cancer. Treatment options do not vary greatly between cell types.

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Epithelioid

Epithelioid mesothelioma is the most common type of mesothelioma cancer cell and constitutes approximately 50% to 70% of all malignant mesothelioma. This is the least aggressive of the cell types, and it generally responds well to treatment. Individual epithelioid mesothelioma cells are shaped like cubes or multi-sided boxes and they have a tubular papillary structure. Due to the fact that other types of cancer can take a similar form, they can easily be confused with epithelioid mesothelioma if they appear in the mesothelium. Adenocarcinoma is one type of cancer that is often confused with epithelioid mesothelioma.

Sarcomatoid

Sarcomatoid mesothelioma accounts for approximately 7% to 20% of malignant mesothelioma. It is the most aggressive cell type and generally does not respond well to treatment. As a result, the prognosis with the sarcomatoid mesothelioma cell type is generally considered poor. Sarcomatoid cells are typically spindle-shaped or oval. Sarcomatoid mesothelioma can also easily be confused with sarcomatoid carcinoma and sarcoma because the irregular oval shape is common among cancer cells. When examined under a microscope, the nuclei is less visible than the nuclei of epithelioid mesothelioma cancer cells.

Biphasic

The biphasic, or mixed, cell type is a combination of elements of both the epithelial and sarcomatoid cell types. The biphasic type can occur when the two types of cells are intermixed continuously throughout the tumor, or when they are found in specific groupings throughout the tumor. This cell type makes up 20% to 35% of mesotheliomas. Biphasic mesothelioma cancer can be an easier to diagnose than either sarcomatoid or epithelioid because patients have two very different mesothelioma cell types associated with their disease, which makes it less likely to be confused with a variety of other cancers.