Epithelioid Mesothelioma

There are two basic classifications for mesothelioma cancer cells; those are epithelioid and sarcomatoid.  There are sub-classifications of these cells for rare forms of mesothelioma that affect, for example, the testes; but the two designations generally define the type of mesothelioma in a diagnosis.

The term epithelial refers to the cells that line both internal and external surfaces of the body.  Epithelial carcinoma is cancer that begins in the cells lining an organ.  The mesothelium is the membrane that lines the outer surfaces of the lungs and heart, as well as the walls of both the chest cavity and the abdominal cavity.  Epithelioid mesothelioma, then, is cancer that begins in the membrane lining the outer lung surface and specifically in the cells that form the membrane.  Epithelioid cancer cells are epithelial cells that have malfunctioned and begun to uncontrollably reproduce malignant cells. 

Epithelioid mesothelioma is the most common form of the disease; it is the primary diagnosis in well over half of all mesothelioma cases.  The epithelial cells are impacted by asbestos fibers that are inhaled by the eventual cancer patient.  Over a period of years – sometimes twenty or more – the asbestos fibers work their way through the wall of the lung into the mesothelium, the membrane lining the outside of the lung.  Eventually the epithelioid cells may find their way to the membrane lining the chest wall. 

The space between these two membranes is called the pleural area; one of the most common symptoms of epithelioid mesothelioma is pleural effusion, when fluid accumulates in the pleural area causing pleural effusion - a condition wherein the fluid puts pressure on the lungs, causing chest pain and shortness of breath.

Cancerous epithelial cells have a distinctive shape that can be misdiagnosed under the microscope and defined as another type of cancer known as adenocarcinoma, a form of cancer that also begins in the tissue around the lungs. The shape of epithelial cells is a flattened form that sometimes has a cubical appearance in its nucleus. Before much was known about mesothelioma and its origin in the epithelial cells, it was not uncommon for a case of epithelioid mesothelioma to be mistaken for adenocarcinoma.

treatment of epithelioid mesothelioma is generally a multi-faceted approach, the components of which are dictated by the degree to which the cancer has advanced along with the general health and age of the patient.  If resection is still a possibility, a surgeon will remove sections of the mesothelium that have been impacted by epithelioid cancer cells.  The surgery may include removal of all or a portion of the lung as well.

With or without surgery, treatment of mesothelioma usually calls for a combination of chemotherapy and radiotherapy; sometimes the initial radiation treatment is given during the surgical process.  Slowing the progress of mesothelioma is usually chemotherapy that involves multiple drugs, attacking the malignant cells in a variety of ways.  Because epithelioid mesothelioma is the most common of mesothelioma diagnoses, it is the simplest to treat.  It involves one category of cancer cell that can be checked through the use of medicines known to have an effect.

It is a complicated disease even in its simplest form however, and that is why clinical trials continue seeking ways to more effectively limit the growth of epithelioid mesothelioma and thereby extend the patient’s survival period after diagnosis.  For information on clinical trials, visit the National Cancer Institute’s list of over six thousand clinical trials now accepting patients.