Types Of Mesothelioma
Types of Mesothelioma: Pleural, Peritoneal, and Pericardial
Different types of mesothelioma are determined by examining the location and cellular makeup of tumors of the mesothelium, the protective lining surrounding internal organs, as well as abdomen and chest walls. Mesothelioma begins within the mesothelium and is named according to where the cancerous cells began to develop. For example, cancer that develops in the lung’s mesothelium, known as the pleura, is named “pleural mesothelioma”.
Mesothelioma types are identified by three criteria:
- The type of cancer discovered in the mesothelium - benign or malignant
- The mesothelioma cancer cell types found in the tumor – epithelioid, sarcoma, or both
- The location of cancer cells and where in the mesothelium they began – pleura (lungs), peritoneum (abdomen), or pericardium (heart).
How Different Types of Mesothelioma Develop
Because mesothelioma is so rare, particularly those affecting the abdominal organs and heart, information about the different types of mesothelioma is limited. However, asbestos was known to cause respiratory illnesses as early the turn of the 20th century when an abstract titled “Curious Bodies” was published that detailed the first known case of complications in a person who had been exposed to asbestos (later termed “asbestosis”). This paper was published a mere twenty years after the first industrialized use of asbestos materials. Through many years of related deaths and research, we now know that asbestos exposure plays a key role in the development of malignant types of mesothelioma.
Pleural mesothelioma is well documented as the most common type of mesothelioma. This type of mesothelioma occurs in the lungs and makes up about 75% of all cases of mesothelioma. Because it is the most prevalent type of mesothelioma, cancer experts have been able to determine that pleural mesothelioma develops between twenty and fifty years after exposure to asbestos.
Experts also identified the likely reason that asbestos causes his type of cancer. When asbestos fibers are inhaled they stick into the inside of the lungs where, over a period of many years, the fibers begin to cause cell mutations. How this comes to affect the pleura on the outside of the lungs is still part of the mystery that researchers are attempting to solve.
Pericardial mesothelioma, cancer of the heart’s mesothelium, and peritoneal mesothelioma, cancer of the abdominal mesothelium, are much rarer and offers fewer opportunities for research. In cases of pericardial types of mesothelioma, cancer may occur because of asbestosis particles that make their way into the blood stream. Peritoneal mesothelioma may begin to develop when particles are swallowed, such as coughing and then swallowing or eating without washing the dust from one’s hands.
Malignant and Benign Types of Mesothelioma
Benign types of mesothelioma are not cancerous and typically not life-threatening. There are rare cases in which a benign tumor can prohibit blood flow or apply pressure to the spine, which can result in other complications. In most cases of benign cancer, even those that cause other complications, tumors are easily removed during surgery. Though these cases are scarce, some cases of benign fibrous tumors (about 1 in 10) turn into malignant mesothelioma.
Malignant types of mesothelioma are cancerous and very life threatening. The prognoses for malignant mesothelioma types are often bleak. Early detection is the key to survival with any type of cancer. Since mesothelioma tends to have a longer latency period (the period of time from exposure until symptoms begin to be presented), early detection typically happens accidentally. Once the mesothelioma type is identified, life expectancy is typically less than a year (approximately nine to twelve months). However, statistics apply to groups and not individuals. There are twenty year survivors of mesothelioma and, statistically, about 5% survive for five years or more.
Mesothelioma Cell Types
A histopathologist is often called upon to perform a biopsy to help determine the type of mesothelioma. During the biopsy, this medical specialist removes cells from a tumor and then examines them under a microscope. In a growing trend, it is common for the histopathologist to draw cells from various points on the tumor. This is a new trend in biopsies because finding more than one cell type within a single tumor can provide a vast amount of differentiation between mesothelioma and other conditions that share the same symptoms and indicators. There are three terms used to identify the cell types, epithelioid, sarcomatoid and biphasic mesothelioma.
Epithelioid Mesothelioma Types
The most commonly occurring cancer cell related to mesothelioma is epithelioid cells. Epithelioid cells are identified by their cube shape and have a distinctive nucleus when viewed under a microscope. These cells can be confused for adenocarcinoma, so any history of asbestos exposure should be disclosed to histopathologists and doctors. This mesothelioma cell type occurs in 50 – 60% of malignant mesothelioma cases.
Sarcomatoid Mesothelioma Types
Sarcomatoid cells are much less common, occurring in less than 20% of malignant cases. Sarcomatoid cells are less uniform than those present in epithelioid types of mesothelioma and tend to be oval in shape with no clear nucleus. This cell can be confused with a variety of other conditions, as well. A sub-type of sarcoma mesothelioma, desmoplastic mesothelioma is a very rare type of mesothelioma in which 50% or more of normal connective tissue cells are replaced with collagen cells.
Biphasic Mesothelioma Types
Biphasic refers to the presence of sarcomatoid cells and epithelioid cells within a single tumor. Patients with biphasic mesothelioma are easier to diagnose.
Malignant Types of Mesothelioma
Malignant mesothelioma types are those that are cancerous and life threatening and are named according to which part in the mesothelium the cancer initially began to develop. The primary malignant types are pleural mesothelioma, pericardial mesothelioma, and peritoneal mesothelioma. Any malignant type can spread to other parts of the mesothelium, so determining the origin of the cancer is often a matter of determining which part of the lining is most affected.
In terms of treatment, the options are the same for the different types of mesothelioma and depend on the patient’s prognosis. In later stages of any mesothelioma type, cancer spreads to other organs and surfaces. That is to say that the cancer can begin on the lungs and spread to the esophagus, trachea, muscle tissues, ribs, spine, and any nearby mesothelium. Mesothelioma in the abdomen may spread to reproductive organs in the pelvis and mesothelioma around the heart can travel further into the heart or to the surrounding organs such as lungs, esophagus, and trachea.
- Pleural Mesothelioma
Pleural is a type of mesothelioma that originates on or in the chest cavity around the lungs. The mesothelium that protects the lungs is known as the “pleura”. 75% of all mesothelioma cases are pleural mesothelioma.
- Pericardial Mesothelioma
Pericardial is a type of mesothelioma that originates around the heart. The mesothelium that protects the heart is the “pericardium”, also known as the pericardial sac. - Peritoneal Mesothelioma
Peritoneal is a type of mesothelioma that originates somewhere in the abdomen. The mesothelium around the abdomen is known as the “peritoneum”.
Benign types of mesothelioma
Benign mesothelioma types are those which are not cancerous and rarely life-threatening. Though surgery can be invasive depending on the location of the tumor these types of mesothelioma can be easily removed through surgery. Some benign mesothelioma types can cause complications with blood flow and circulation if they are growing to apply pressure on nerves or blood vessels. In rare cases, benign types of mesothelioma will also create spinal pressure that can lead to a number of neurological symptoms, making the real cause – the mesothelioma tumor –difficult to find.
Adenomatoid Tumors
Adenomatoid tumors are a type of mesothelioma that originates in the mesothelium of the fallopian tubes in women, the duct that leads away from the ovaries. In men, this mesothelioma type begins in the epididymis, a series of ducts that lead sperm out of the testicles.
Benign Cystic Mesothelioma
Benign cystic mesothelioma is a type of mesothelioma in which cysts form near the reproductive organs. Cysts may or may not reappear after initial treatment.
Solitary Fibrous Tumors
Solitary fibrous tumors can develop in the pleura or peritoneum and aren’t always benign. When they are not benign, they are categorized under one of the malignant mesothelioma types.
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