1. Epithelial cell type - has the most favorable prognosis and is the
    most common
2. Fibrosarcomatous cell type - carries the worst prognosis
3. Mixed cell type - has an intermediate prognosis

Symptoms
The most common symptom of malignant mesothelioma is chest pain or shortness of breath. If you feel you may have mesothelioma from asbestos exposure, it is best to consult with your physician immediately. Common symptoms include:

• Chest pain
• Shortness of breath
• Pleural effusion – fluid in the chest
• Abdominal pain and swelling
• Cough
• Fatigue
• Unexplained weight loss

Diagnosis
As with any serious disease, diagnosing mesothelioma begins with a thorough medical history and a complete physical examination. Three common diagnostic procedures are:

1. A chest or abdominal X-ray – A painless procedure that can take as little as one minute to more than an hour, depending on the areas examined. X-rays allow doctors to view the inside of the lungs and abdomen to determine if there is any obstruction or unusual growth.

2. Computed Tomography (CT) – Another painless procsude that uses X-ray and computer technology to show cross-sectional images of the body at different planes. The result of a CT scan is a series of X-ray pictures of slices of the body, showing what's inside at each specific level. CT’s generally last between 20 minutes and an hour.

3. Magnetic resonance imaging (MRI) – An MRI is also painless and generally takes about 20 minutes to complete. During an MRI, your body is in a very strong magnetic field which uses pulses of radio waves to create a 3-D image of any part of the body. MRI’s are particularly good at detecting tumors and abnormalities in soft tissues.

After determining if fluid is present in the pleura or peritoneum, a thin needle may be used to collect a small sample of the fluid for examination. This procedure, called fine-needle aspiration, also may be used to drain the fluid to relieve symptoms such as chest pain and shortness of breath that can result from an effusion.

Occasionally, mesothelioma can be diagnosed with this fluid sample alone, but usually a tissue sample (biopsy) is required. The tissue sample can be obtained via thoracoscopy (for a pleural tumor) or via laparoscopy (for an abdominal tumor). In both procedures, a tube-like instrument inserted through a small incision allows the physician to view the tumor and collect a tissue sample.

Stages
After malignant mesothelioma is diagnosed, it is important to determine what stage the disease is at. This helps determine what treatment options are available. The staging system most often used for mesothelioma is the Butchart system. This system is based mainly on the extent of the primary tumor mass, and divides mesotheliomas into stages I through IV. The stages of malignant mesothelioma are:

Stage I
The tumor is found in the right or left side of the pleura with or without some involvement of the lung, pericardium (lining of the heart) or diaphragm. Stage I is also called “localized disease” and generally has the best prognosis.

Stage II
The tumor is found in a Stage I location, plus there is involvement of some lymph nodes in the chest. Stage II (and Stage III) are also called “advanced disease.”

Stage III
The tumor has extended into the chest wall, ribs or heart, through the diaphragm or into the peritoneum (the abdominal lining). There also may be involvement of the lymph nodes or esophagus.

Stage IV
The tumor has spread through the bloodstream to distant sites (the cancer has metastasized).

Recurrent Mesothelioma
The tumor has recurred after treatment.

Another staging system has recently been developed by the American Joint Committee on Cancer (AJCC). This is a TNM system, similar to staging systems used for most other cancers. T stands for tumor (its size and how far it has spread to nearby organs), N stands for spread to lymph nodes and M is for metastasis (spread to distant organs). In TNM staging, information about the tumor, lymph nodes, and metastasis is combined in a process called stage grouping to assign a stage described by Roman numerals from I to IV. Minor differences exist between the AJCC TNM staging system and the Butchart staging system. The TNM stages are:

Stage I
Mesothelioma involves the right or left pleura. It may also have spread into the lung, pericardium, or diaphragm on the same side. It has not yet spread to the lymph nodes.

Stage II
 Mesothelioma has spread from the pleura on one side to the nearby peribronchial and/or hilar lymph nodes next to the lung on the same side. It may also have spread into the lung, pericardium, or diaphragm on the same side.

Stage III
 Mesothelioma has spread into the chest wall muscle, ribs, heart, esophagus, or other organs in the chest on the same side as the primary tumor, with or without spread to subcarinal and/or mediastinal lymph nodes on the same side as the main tumor. Subcarinal nodes are located at the point where the windpipe branches to the left and right lungs. Mediastinal lymph nodes are located in the space behind the chest bone in front of the heart. Mesotheliomas with the same extent of local spread as in Stage II that have also spread to subcarinal and/or mediastinal lymph nodes on the same side are also included in Stage III.

Stage IV
 Mesothelioma has spread into the lymph nodes in the chest on the side opposite that of the primary tumor, or directly extends to the pleura or lung on the opposite side, or directly extends into the peritoneum, or directly extends into organs in the abdominal cavity or neck. Any mesothelioma with evidence of distant metastases (spreading to other organs via the bloodstream) or spread to organs beyond the chest or abdomen is included in this stage.

Prevention
To reduce your risk of malignant mesothelioma, you should reduce your exposure to asbestos. Because there is no safe level of asbestos exposure, any asbestos exposure is too much. If you have an older home, check for areas of exposed asbestos-containing insulation or other areas of deteriorating asbestos. These areas must be removed professionally or safely sealed off. Workers who routinely deal with asbestos-containing materials should use approved measures to limit their exposure and to keep from bringing asbestos dust home on their clothing.