Malignant Mesothelioma Types

Malignant Mesothelioma Types, or in particular the cell types, has been histologically classified in three variants, the epithelioid, sarcomatoid and biphasic.

Malignant mesothelioma is a form of cancer that is triggered by exposure to a mineral called asbestos. A non-conductive, non-flammable mineral material, asbestos was heavily mined and used in the United States until the 1970s.

When asbestos dust is inhaled, the microscopic fibers that comprise it can target a certain kind of cells, mesothelial cells, which form the lining around the lungs, heart, stomach and other organs. This lining—the mesothelium—produces a lubricating fluid that allows the organs to move smoothly and without friction. The asbestos fibers can damage it by lodging themselves deep within the cells and causing them to replicate uncontrollably. This leads to the formation of a tumor.

Although there are several types of benign mesotheliomas that can occur, these are relatively rare. Most mesothelioma is of the malignant variety.

Most often, mesothelioma occurs in the chest or abdomen. About three out of four cases of mesothelioma begin in the chest cavity. These are called pleural mesothelioma. Ten to 20 percent begin in the abdomen and are called peritoneal mesothelioma. Mesothelioma can also begin in the membranes surrounding the heart or testicles, but these are extremely uncommon.

Cell Types

There are three main histological categories, or cell of Malignant Mesothelioma Types. They are epithelioid, sarcomatoid and biphasic. While diagnostic techniques for all types of mesothelioma include x-ray, CT or MRI scans and biopsies of tissue samples, determination of which cell type of mesothelioma is present in a patient is done by examining the cancerous cells under an electron microscope.

Epithelioid mesothelioma is the most common of Malignant Mesothelioma Types. Between 50 and 70 percent of mesothelioma cases are epithelioid, which means that the cancer has originated in the epithelial cells in tissues surrounding the internal organs. Epithelial cells have a uniform, cube-like shape, a tubular pattern, and a unique cell nucleus. The symptoms of epithelioid mesothelioma may include fluid build-up, respiratory difficulty and chest pain. Epithelioid mesothelioma can easily be confused with another form of cancer, called adenocarcinoma.

Epithelioid is considered the most treatable form of the cancer, with a better prognosis than the other forms.

Sarcomatoid, or fibrous, mesothelioma is the least common type of mesothelioma. The cells of this form appear originate in the body’s connective tissues, and appear under a microscope as elongated, irregular spindle shapes that often overlap. Occurring in only seven to 20 percent of patients, sarcomatoid mesothelioma is frequently mistaken for sarcomatoid carcinoma, sarcoma, pulmonary sarcomatoid carcinoma, and high-grade sarcoma.

Sarcomatoid mesothelioma cells can further divide into several other types of cancerous cells, including acinar cell, clear cell, small cell, and tubulopapillary cell. Sarcomatoid mesothelioma cells tend to show more abnormality than epithelioid ones, are more aggressive and show more mitotic activity, which refers to the process of cell division and reproduction.

Because of this aggressive and rapid division, sarcomatoid mesothelioma is often considered to be more difficult to treat than the other types.

The last cell type of malignant mesothelioma is a mixture of the other two and is therefore called biphasic mesothelioma. The second most common histological category, diagnoses of biphasic (also called mixed biphasic) mesothelioma have increased in recent years, and now account for 25 to 40 percent of all malignant mesothelioma cases. Biphasic mesothelioma does not have its own distinct cell structure, but rather exhibits both sarcomatoid and epithelioid cells, making it easier to diagnose. Different parts of the tumor may contain different cell types; some oncologists believe that the more tissue samples or biopsies that are taken, the greater the chance of a biphasic mesothelioma diagnosis.

Treatment Options

No matter the histological Malignant Mesothelioma Types that has been diagnosed, the treatment plan will depend primarily on the stage at which the cancer was diagnosed, its location and the patient’s general state of health. The patient and physician together will determine whether to pursue traditional treatment methods such as chemotherapy, radiation or surgery; experimental treatment through clinical trials; alternative approaches; or hospice care and pain management methods. However, some chemotherapy drugs that are effective at destroying the proteins found within epithelioid cells contain enzymes that sarcomatoid cells can resist. Therefore, in the case of a sarcomatoid diagnosis, treatment may be modified.

All Malignant Mesothelioma Types are incurable, with an expected life span of only six to 18 months after diagnosis.