Mesothelioma, like all other types of cancers, can be divided into two broad groups: benign and malignant.
Benign mesothelioma refers to non-cancerous tumors developing usually in the pleura (cell lining around the lungs). The main difference between the benign and the cancerous form is that the former does not spread to other tissues. However, the symptoms of both the benign and the malignant form are the same and it is often difficult to distinguish between the two except through lung biopsies. However, less than 10% of cases of mesothelioma are benign. In half of the cases of benign mesothelioma, there are no symptoms at all.
Patients may learn of the disease through routine X-Ray scans of the lungs. In the other half, benign mesothelioma symptoms include: chest pain, chronic cough, and fever. However, the most distinguishable characteristic is the presence of clubbed fingers. This arises when the blood oxygen level falls resulting in distorted angles in the nail beds. Benign mesothelioma treatment is comparatively easy. It involves removal of the tumors surgically. Patients must continue to have regular check-ups and chest x-rays to ensure that the benign mesothelioma does not develop in its malignant form.
Malignant mesothelioma is the most common form of the disease. This type of mesothelioma can be further classified into the location where the malignant tumor arises or the type of cancer cells produced. Classification into the location of the cancer gives three types of mesothelioma cancer:
(i) Pleural mesothelioma: this arises in the protective lining and the cavity of the lungs. Most of the symptoms associated with it arise due to the build-up of fluid between the chest cavity and the lining of the lungs (called pleural effusion). This results in difficulty in breathing, shortness of breath, persistent coughing, coughing up of blood and fever. This is the most common form of mesothelioma cancer representing 75% of all cases
(ii) Peritoneal mesothelioma: this is the development of cancer in the stomach and the abdomen. The cancer usually starts in the abdominal area and spreads to other parts of the body. Symptoms are due to the pressure of the tumor on the stomach and the abdomen, causing abdominal pain, swelling, loss of appetite, vomiting, breathing problems, anemia and a host of other symptoms. Peritoneal mesothelioma accounts for 10-20% of mesothelioma cases.
(iii) Pericardial mesothelioma: this affects the lining of the heart cavity. Symptoms include chest pain, shortness of breath and palpitations. This is the rarest form of mesothelioma, representing less than 10% of cases.
Another way to classify mesothelioma is through the type of cancerous cells that arise. There are basically two types of mesothelioma cells: epitheloid and sarcomatoid. Epitheloid cells arise in the lining of the organs only. The chances of survival are greater with this type of cancer. Sarcomatoid cells are more difficult to treat as it affects secondary tissues such as bones, muscles, cartilage…etc. This type of cancer rarely responds to any form of treatment. In cases where both types of cells arise, it is known as biphasic mesothelioma.