Malignant Mesothelioma vs. Benign Mesothelioma

Get your free case evaluation

Malignant mesothelioma (usually referred to only as mesothelioma) is a disease in which the lining of the chest, heart, lungs or abdomen develops cancer.  In almost all cases, mesothelioma is caused from exposure to asbestos. The small asbestos fibers enter the body through ingestion or inhalation and embed in the mesothelium. Inflammation results which can lead to fluid build-up and the growth of tumors. Most mesothelioma tumors are cancerous (malignant).  However, about 10% of mesothelioma tumors are noncancerous (benign).

Understanding the Mesothelial Cell 

Mesothelial cells are not really something you think about unless a problem develops. The cells form a layer or membrane that lines serous cavities and organs. Serous cavities is the term used for body cavities that are lined with cells that secrete a serous or lubricating fluid.

The amazing structure of the human body is such that it virtually “oils” itself like an engine. The internal organs are constantly moving and one of the purposes of the serous fluid is to provide a slick surface making movement easier. The membrane also serves as a protective surface for the cavity and especially the organs. Mesothelial cells are critical to the human body and are also involved in the transportation of fluids between body cavities and the transportation of cells for tissue repair or to combat inflammation.1

For tumor cells to take root and grow into masses in the mesothelium, they must first find a way to infiltrate the membrane. When asbestos fibers becomes embedded in the mesothelium, they provide the wound that tumor cells need for infiltration and attachment. In fact, the fibers can cause membrane inflammation that leads to cell mutations and the mutated cells have the perfect setting for growth. However, not all mutated cells are cancerous.

More than 50 percent of metastasized primary chest wall tumors are due to cancer that began in a distant area of the body or are the direct result of cancer growing into the chest wall from nearby malignancies including breast cancer and mesothelioma. A biopsy should always be  done to make a definitive determination of the type of tumor and its source.2 Clearly though, malignant mesothelioma can lead to tumor development in more than one way.

Difference between Malignant and Benign Mesothelioma 

When a doctor detects any type of tumor, it can be a frightening experience. Until you know whether the tumor is benign or malignant, you fear it is cancer. A benign tumor is one that is self-contained and is therefore not cancerous. The cells in a benign tumor will replicate, but they will not metastasize (spread) nor will they invade the surrounding healthy tissue. These types of tumors tend to grow slowly and often their worst consequence is that the tumor presses on important organs, nerves or blood vessels creating medical issues.

A malignant or cancerous tumor, on the other hand, will spread. It performs in the exact opposite way of a benign tumor. The malignant tumor can metastasize and invade healthy tissue and destroy it. The tumor may spread the cancer by releasing cancer cells that enter the blood stream or the lymphatic system. The cancer cells then travel to other parts of the body where they attach to tissue and grow into tumors or destroy healthy cells.

So the primary difference between malignant and benign mesothelioma is that the former can spread to healthy tissues throughout the body whereas benign mesothelioma stays localized.  Thus, benign mesothelioma has a much better prognosis and is often not life threatening if treated promptly. Because malignant mesothelioma can rapidly spread throughout the body, curative treatment is very difficult and in some cases impossible.

With malignant mesothelioma, there is usually a prolonged latency period of over a decade.  Benign mesothelioma differs as it may appear soon after asbestos exposure.  Patients who have been diagnosed with benign mesothelioma should be screened regularly for other asbestos-related diseases.

Dangers of Benign Mesothelioma

Benign mesothelioma is also called “solitary fibrous tumor of the pleura” or “solitary fibrous tumor of the peritoneum” depending on where the tumor is located. It is normally a tumor that first develops in the submesothelium tissue (under the mesothelium membrane). 

Just because benign mesothelioma is not cancerous, it does not mean that it isn’t dangerous.  The benign tumors can rapidly grow large and put pressure on organs, nerves, or other tissues. This can result in complications like seizures or coma. Because mesothelium is responsible for lubricating certain organs, benign tumors and inflammation can interfere with the fluid process and lead to effusion – a condition in which too much fluid accumulates in the layers of the membranes lining the chest and abdomen cavities and covering the internal organs. Breathing can become very difficult and there may be pain.

The mesothelial cells are not fully understood yet. They appear to play a much larger role in the body than originally believed. For example, it has been suggested that these remarkable cells may be able to switch between various cell phenotypes depending on the body’s needs.3 Therefore, damage to these cells for any reason, including mesothelioma, most likely has a greater impact on health than is understood even when a tumor is benign.

Diagnosing Benign Mesothelioma 

Benign mesothelioma has the same symptoms as malignant mesothelioma.  These symptoms differ depending on where the mesothelioma is located but can include:

  • Pains in chest, shoulder, arms, or abdominal area
  • Breathlessness
  • Unexplained weight loss
  • Unusual fatigue
  • Chronic coughing

The various types of mesothelioma are usually first diagnosed with an image scan, such as a CT scan or x-ray.  These scans will only tell the doctor the size and location of the suspected mesothelioma.  The scans will not be able to tell whether the mesothelioma is benign or malignant.  To confirm mesothelioma and determine its type, the doctor will perform a biopsy in which a small amount of tissue or fluid is removed from the infected area and analyzed in a lab.

Treating Benign Mesothelioma 

Treatment for benign mesothelioma involves surgically removing the tumors or compromised tissue area. In most cases, surgery alone is adequate to fully remove the tumor. The prognosis is very good with most patients having a speedy recovery.  However, recurrences of benign mesothelioma do occur in about 10% of cases so patients should regularly be checked by their doctors.

Options for Patients 

Just because benign mesothelioma is not life threatening, that does not make you less of a victim from asbestos exposure. You may be entitled to compensation through legal action. An experienced mesothelioma lawyer can tell you more about your rights and seek compensation on your behalf to pay for medical and living expenses.


1 Mutsaers, S. E. (January 2004) The mesothelial cell. International Journal of Cell Biology., v1:9-16. 

2 Geka, Kyobu. (July 2011) Chest wall tumor, rib tumor. Department of Thoracic Surgery, Kumamoto University.v64(8 suppl) 725-32 at

3 Herrick, S. E. and Mutsaers S. E. (April 2004) Mesothelial progenitor cells and their potential in tissue engineering. International Journal of Cell Biology. v4: 621-42.