There are four types of mesothelioma.
The mesothelioma types are:
- Pleural mesothelioma
- Peritoneal mesothelioma
- Pericardial mesothelioma
- Testicular mesothelioma
Each type is named for the location where it begins inside the body.
Also, each type of mesothelioma is further differentiated by whether it is malignant or benign. Malignant mesothelioma is that which has spread from its location of origin. Benign mesothelioma is that which has not spread.
Pleural mesothelioma is the most common type of mesothelioma. Approximately three-quarters of all mesothelioma cases are of this one type. As well, pleural mesothelioma usually strikes people who are over the age of 50. Men are more likely than women to develop pleural mesothelioma.
It is called pleural mesothelioma because it begins on the thin lining of tissue that surrounds the lungs. This lining is known as the pleura.
To understand how pleural mesothelioma is different from the other three types of mesothelioma, the best place to start is with an anatomy lesson. And the best starting point for that lesson is the lungs.
The lungs are the organ that convert inhaled air into usable oxygen for the blood circulating throughout the entire body. The lungs also process the gaseous waste (carbon dioxide) produced by blood metabolic activity and expel it back out into the air.
The body has two lungs, one on each side of the chest. Each lung contains multiple lobes—three in the lung on the right side and two in the lung on the left (the left has fewer than the right to provide room for the heart).
The lungs are soft and very elastic. Air enters each lung through, first, the trachea (also known as the windpipe) and then through a connecting tube-like structure called the bronchus (also known as the large airway). Within the lung, the bronchus splits into a series of smaller branches. The branches in turn split into even smaller stems at the ends of which are clusters of tiny air sacs. The entire arrangement looks like a leafy tree turned upside down.
The air sacs are known as alveoli. It is within these sacs that inhaled oxygen molecules are transferred to the blood in exchange for carbon dioxide molecules.
Each lung is surrounded by its own self-contained pleura. The pleura is made up of two thin sheets of flat cells. One layer is called the visceral pleura. The other is called the parietal pleura. The visceral pleura wraps around the lung, while the parietal pleura lays over the interior of the chest wall.
Between the visceral and parietal pleurae is a small space filled with a slick fluid that acts as a lubricant. This lubricant allows the lungs to expand during inhalation without causing pain as they rub up against the inside of the chest wall.
The pleura is vulnerable to a variety of diseases, not just mesothelioma cancer. For example, it can fall prey to pleurisy, which is a form of inflammation. Sometimes, the pleural space can fill with blood, a condition known as hemothorax. Another disease that can affect the pleura is empyema, an accumulation of pus in the pleural space.
For pleural mesothelioma patients, one major disorder that typically results is pleural effusion. This is a condition in which the pleura spews a large volume of fluid into the chest cavity. The fluid has nowhere to go, so it just keeps building up. As it does, it takes up the space meant for the lung. Gradually, the fluid collapses the lung, rendering it useless and leaving the mesothelioma patient struggling for air.
It is called peritoneal mesothelioma because it begins on the thin lining of tissue that surrounds the interior of the abdomen. This lining is known as the peritoneum.
Like the pleura, the peritoneum consists of two thin sheets of flat cells. Between these layers—one is called the visceral peritoneum and the other is known as the parietal peritoneum—there is a very narrow space that contains 50 ml to 100 ml of lubricating fluid.
Blood circulating through the vessels woven within the abdominal wall nourish the parietal peritoneum, which also receives blood from arteries coursing around the iliac and lumbar spine. Meanwhile, the visceral peritoneum is fed by blood from the superior and inferior mesenteric arteries.
The parietal peritoneum lines the inside of the abdominal cavity. The visceral peritoneum covers the organs that bump up against the inside wall of the abdominal cavity—these organs include the stomach and intestines (but not all organs that extend into the abdominal cavity are wrapped within the visceral peritoneum).
Toward the back of the abdominal cavity, the intestines are protected by a double layer of the parietal peritoneum (there is no space between these layers). This double layer is referred to as the mesentery. In addition to helping hold the intestines in place, the mesentery also makes sure the intestines receive an adequate supply of blood from nearby vessels and nerves.
When any of these peritoneum membrane surfaces become damaged, they interfere with the healthy functioning of organs such as the stomach, kidneys, and liver. Mesothelioma produces damage of the type that can cause just such interference.
Pericardial mesothelioma begins on the pericardium. The pericardium is a sheet-like, flat-celled protective membrane that surrounds the heart.
The role of the pericardium is to constrain the heart so that it cannot expand too much. Over-expansion creates a dangerous health risk because the heart then becomes gorged with blood.
The pericardium also serves as a shield to ward off infections from the lungs (the two lobes of the lung on the left side of the body are in extreme proximity to the heart). This shielding is especially important because of the relative ease with which lungs can become infected.
Perhaps the most important function of the pericardium is to ensure that the heart can freely beat without causing pain. Absent the pericardium, the heart would bump up without cushioning against the inner wall of your chest cavity. Each beat of the heart would produce pain but as well significantly interfere with the pumping of blood.
The pericardium consists of two layers (technically, three). The first layer is called the fibrous pericardium. Its thick connective tissues anchor to the sternum, diaphragm, and spine. This anchoring secures the heart and prevents it from shifting position inside the chest cavity.
The second layer is called the serous pericardium, itself made up of two layers—the visceral and the parietal. The parietal layer of the serous pericardium abuts the fibrous pericardium. The visceral layer of the serous pericardium lines the exterior of the heart.
In between the serous pericardium’s visceral and parietal layers is a narrow space which holds a small quantity of lubricating fluid. The slick fluid allows the fibrous and serous pericardia to glide across one another. The fluid also allows the heart to beat freely.
Significant health problems can result when the pericardium becomes irritated. The irritation usually leads to swelling or fluid overproduction or both. Either one can interfere with the proper workings of the heart and trigger damage. For example, excess fluid (pericardial effusion) can bring about a condition known as cardiac tamponade in which the heart—straining and struggling to expand and contract—fails to deliver enough blood throughout the body. Excess fluid can also inflict damaging pressure on the heart.
Mesothelioma can cause irritation of the pericardium as well as pericardial effusions.
Testicular mesothelioma is the name given to the type of mesothelioma that begins on the tunica vaginalis propria testis—the protective membrane surrounding the testes, part of the reproductive system in males.
The tunica vaginalis propria testis is an extension of a structure that extends out of the peritoneum. That extension structure is named the saccus vaginalis. It consists of a visceral layer and a parietal layer, as do the other types of protective membrane linings discussed above.
Mesothelioma develops on the surfaces of the tunica vaginalis propria testis when the cells making up the visceral and parietal layers mutate. The mutations usually take the form of stony, yellowish-white nodules that increase membrane thickness.
The tendency of mutated cells in this location is to multiply and spread rapidly to other nearby organs, which include the liver, kidneys, and digestive tract. The spread can also involve vital tissues.
Talk to a mesothelioma lawyer
Regardless of the type of mesothelioma, the fight that follows can be a hopeful one. Even so, it is almost certain to also be expensive. There will be doctor and hospital bills, and likely a loss of income to pay for costs not covered by insurance.
That is why it is a good idea to talk to a qualified mesothelioma lawyer. If you or a loved one has one of the four types of mesothelioma discussed in this article, a qualified mesothelioma lawyer can explain how to obtain financial compensation for this disease.
Mesothelioma is a cancer caused by the negligence and, in some instances, the bad intentions of companies that made, sold, distributed, or utilized the mineral asbestos in some commercial manner. These companies can be held legally liable for the harms they caused.
To talk to a mesothelioma lawyer today.
About the author…
Gregory Sandifer graduated from Southern Illinois University Edwardsville and received his law degree from Western State University College of Law in Fullerton, California.