Mesothelioma is a specific type of cancer overwhelmingly caused by exposure to asbestos. It involves mesothelial cells that form the very thin linings/membranes surrounding and encasing the lungs, heart, abdominal cavity, and gonads. These linings are called the serosal membranes or mesothelium. After a person inhales or ingests asbestos fibers, those fibers reach the mesothelium where they cause genetic errors of the mesothelial cells that comprise the membranes. This results in daughter cells without the ability to control cell growth. This loss of controlled cell growth can lead to cancer of the mesothelial cells, which is mesothelioma.
It is Rare for Mesothelioma to Spread to the Brain
Mesothelioma brain metastasis is possible, however, it is extremely rare, even in the late stages of the disease, and only occurs in an exceptionally small percentage of patients. In the few known cases of mesothelioma brain metastasis, tumors have been found in the cerebral cortex, the cerebellum, and the brain stem, however, are often not discovered until post-mortem. Local progression of the tumor as it rapidly grows is the much more common method of mesothelioma spread rather than distant metastasis. Therefore, mesothelioma most commonly spreads to the tissues and organs within the chest and abdomen. Most typically, it spreads from one pleura to the other pleura, the pericardium, or the peritoneum.
Types of Mesothelioma and Areas of the Body They Effect
There are four different types of mesothelioma. The type is determined by the area of the body that is directly affected by cancer:
Pleural mesothelioma develops in the pleura, the two-layer lining of the lungs. It commonly begins in the parietal pleura (the outer lining of the lung) on one side of the chest and then advances to the visceral pleura (the inner lining of the lung surface) on the same side of the chest. As an advance, pleural mesothelioma can spread to lymph nodes and the lung tissue itself on the same side of the chest, as well as the diaphragm (the thin muscle below the lungs and heart), the mediastinum (the space in the chest between the lungs), and the tissue and muscle of the chest wall, but more often spreads to the adjacent serosal membranes. In later stages, pleural mesothelioma is known to spread to the pleural and lung tissue on the opposite side of the chest, to the pericardium (the two-layer lining of the heart), to the muscle of the heart itself, to organs within the mediastinum including the esophagus, thymus, and trachea, and can even spread through the diaphragm and into the peritoneum (the two-layer lining of the abdomen), and abdominal organs, such as the liver and kidneys.
Peritoneal mesothelioma develops in the peritoneum, the two-layer lining of the abdomen, and can spread to surround the organs within the abdomen including the liver, spleen, stomach, the tissue surrounding the intestines and colon, the intestines and colon themselves, and can also spread up into the chest cavity and the tissue and organs within.
Pericardial and Gonadal Mesothelioma
Pericardial mesothelioma which develops in the pericardium, the two-layer lining of the heart, and gonadal mesothelioma which develops in the tunica vaginalis, the lining of the testes, are both rare forms of mesothelioma, occurring in less than 1% of all cases. Due to the infrequency of occurrence, less is known about the progression of pericardial and gonadal mesothelioma, however, like pleura and peritoneal mesothelioma, these forms are generally thought to spread locally rather than metastasize to distant organs.