Mesothelioma is a rare disorder and is often misdiagnosed. It is a disease that derives directly from the mesothelial cells in the serous membranes. But it is not uncommon for other growths to appear in the mesothelium, both cancerous and non-cancerous.
Tumors of the mesothelium can be benign (non-cancerous) or cancerous. A malignant tumor of the mesothelium is called malignant mesothelioma, but because most mesothelial tumors are harmful, the disease is often called merely mesothelioma.
Although uncommon, the mesothelium of certain female and male reproductive organs may develop a benign tumor called an adenomatoid tumor. In men, cancer starts in the area where the sperm is carried from the testicles and in women it starts in the fallopian tubes. Another type of benign tumor that begins in the female reproductive organs is called benign cystic mesothelioma.
A type of benign tumor that used to be called benign fibrous mesothelioma can form in the pleura around the lungs. It is now known that this type of tumor starts in the tissues under the mesothelium and therefore is not a type of mesothelioma.
It is typically not cancerous but can progress to cancer in some cases. A similar disease that forms in the peritoneum is called a fibrous tumor of the peritoneum. These types of tumors are often removed surgically, and no other treatment is needed.
The most common form of malignant tumors in the mesothelium are metastatic tumors. That is, the tumors start in another part of the body, and then cancer metastasizes and spreads to the mesothelium. The ratio is between 7: 1 to 20: 1 for the occurrence of these types of tumors versus mesothelioma. Mesothelioma derives directly from the mesothelial cells and does not migrate into the mesothelium from other organs.
The most common metastatic tumors that grow in the pleura derive from, in descending order:
- large intestine
For the pericardial tumors from metastases, the most common originating organs are lung, breast, and thyroid. In the peritoneum, the ovary, stomach, large intestine, pancreas, and chest are the most common sources of metastatic tumors.
Not all diseases of the lung and mesothelium involve tumors.
Patients with asbestosis, pleural thickening, and interstitial lung disease typically suffer from breathing problems caused by the growth of fibrous tissue, and from pleural effusion, or buildup of fluid, in the pleural space.
To learn more about diseases of the lung and mesothelium, click on the links below.