Mesothelioma occurs when cancer cells form in the mesothelium, which is a thin layer of protective tissue covering most internal organs. This rare disease usually develops after heavy exposure to the natural mineral asbestos, which may be more likely in certain occupations (such as construction, auto repair, or working with insulation).
Mesothelioma presents with similar symptoms to many common conditions, which can lead to misdiagnosis and delays in appropriate treatment. While challenging, early detection is key to improving prognosis for mesothelioma patients.
Types of Mesothelioma
Pleural Mesothelioma
Pleural malignant mesothelioma is the most common form of mesothelioma, accounting for 75 to 80 percent of cases. Each year, approximately 2,500 people in the United States are diagnosed with this disease.
Pleural mesothelioma is caused by needle-like asbestos fibers becoming embedded in the lining of the lungs (called the pleura) after being inhaled or swallowed. The tiny fibers can remain lodged in the body for many years. The result is chronic tissue inflammation, scarring, and genetic damage, which may result in the development of cancer cells that can grow quickly.
Two layers make up the pleural lining: the inner layer covering the lungs and an outer layer that lines the entire inside of the chest cavity (inside the ribs). A malignant tumor can develop on either layer and rapidly spread to the other layer.
As tumors develop on the pleural surface, they begin to form a mass around the lung. They also cause pleural fluid to accumulate in the chest cavity, which is called pleural effusion. The combination of the tumor mass and the collection of fluid prevents the lung from expanding, which can cause breathing difficulties.
Symptoms of Pleural Mesothelioma
- Pain in the chest, rib cage, or lower back
- Persistent dry cough or coughing up blood
- Shortness of breat
- Unusual lumps under the skin on the chest
- Difficulty swallowing
- Unexplained weight loss and fatigue
Peritoneal Mesothelioma
Peritoneal mesothelioma forms in the layer of tissue called the peritoneum, which lines the abdomen and covers most of the abdominal organs. It is the second most common type of mesothelioma and is diagnosed in 15 to 20 percent of cases annually.
Peritoneal mesothelioma can also be caused by asbestos exposure. Fibers that are inhaled or swallowed can become lodged in the abdominal lining after traveling through the digestive or lymphatic systems.
Recent treatment advancements have led to more favorable outcomes for many peritoneal mesothelioma patients. One of the most promising treatments is surgery (cytoreduction) combined with hyperthermic intraperitoneal chemotherapy (HIPEC), which can add years to an individual’s prognosis. Fox Chase surgeons specialize in this sophisticated treatment option.
Symptoms of Peritoneal Mesothelioma
- Abdominal pain
- Abdominal swelling
- Fluid buildup in the abdominal cavity
- Nausea or loss of appetite
- Unexplained weight loss
Other Forms of Mesothelioma
The following forms of mesothelioma (pericardial and testicular) are extremely rare. They may be associated with asbestos exposure, but it is inconclusive how asbestos fibers could cause primary cancer in these areas:
- Pericardial mesothelioma occurs in the lining of the heart (called the pericardium) and develops between two layers of membrane. The tumor thickens the membrane, which may limit heart function and can lead to more serious issues (such as cardiac failure). Pericardial mesothelioma can be difficult to treat because of its proximity to the heart. Surgery and chemotherapy can be used for treatment or as part of palliative care.
- Testicular mesothelioma forms as yellow-white nodules in the lining of the testicles and causes the lining to thicken. Surgery is used as the primary treatment and is often combined with radiation and chemotherapy.
Are All Mesotheliomas Malignant?
There are several extremely rare types of benign mesothelioma that mostly originate in the peritoneum. All of these forms are considered treatable (often with a single surgical procedure):
- Benign multicystic peritoneal mesothelioma (BMPM)
- Well-differentiated papillary mesothelioma (WDPM)
- Benign adenomatoid tumors
- Localized fibrous tumors
