There are different types of mesothelioma. Doctors classify each type of mesothelioma by the location in the body where it develops. Prognosis, symptoms and treatment options vary by type. The pleural and peritoneal types of mesothelioma are the most common, while pericardial accounts for just 1% of cases.
Another rare type known as testicular mesothelioma represents less than 1% of all mesothelioma cases.
Pleural Mesothelioma
Pleural mesothelioma is cancer that develops in the cells that form the outer lining of the lungs and inner lining of the chest cavities. It is the most common type of asbestos-related cancer. Specialists use the latest therapies to treat it, and clinical trials offer access to new treatments such as immunotherapy.
- Most common type
- Forms on soft tissue covering the lungs
- Best treated with a multimodal approach (combination of treatments)
- Symptoms: Shortness of breath, chest pain, dry cough
Pleural Mesothelioma Causes
After a person inhales asbestos dust, the human body struggles to remove the mineral’s needle-like fibers from the lungs. Over a long period of time, trapped fibers migrate to the pleural lining and cause irritation and chronic inflammation.
The trapped fibers cause pleural mesothelioma by triggering genetic changes that turn cells cancerous. These cancerous cells grow fast and uncontrollably, threatening the organs around them.
Two layers make up the pleura lining. The outer layer, called the parietal pleural membrane, lines the entire inside of the chest cavity. The inner layer, or visceral pleural membrane, covers the lungs. A pleural mass can develop on either layer and quickly spread to the other layer. As tumors develop on the pleural surface, they grow to form a sheath-like mass around the lung.
Pleural Mesothelioma Symptoms
Many don’t notice the symptoms of pleural mesothelioma right away. People brush them off, especially the elderly. The early symptoms often mirror signs of less serious respiratory issues, such as pneumonia, bronchitis, and emphysema. These symptoms are a common occurrence for seniors. Then, the symptoms grow more serious. These can be chest pain, slight fatigue or shortness of breath during physical activity.
Once the cancer progresses to a late stage, however, the symptoms become much more specific and acute.
Pleural Mesothelioma Diagnosis
Doctors sometimes mistake pleural mesothelioma for common diseases with similar symptoms, such as the flu or pneumonia. Rare cancer requires extensive testing to diagnose. The diagnostic process begins when a doctor, often a primary care physician, evaluates initial symptoms. Chest pain and breathing impairment warrant a chest X-ray, typically the first test to show fluid or tumors around the lungs.
Referral to a pulmonologist, oncologist or general hospital is common after an abnormal X-ray. Further imaging, blood tests, and tissue biopsies are used to confirm a pleural mesothelioma diagnosis.
It is challenging for doctors to tell the difference between pleural mesothelioma and lung cancer in some cases. While doctors may suspect mesothelioma based on a patient’s scans, symptoms, and history of asbestos exposure, these signs are not enough to confirm a diagnosis.
The most reliable tool to diagnose the disease is a thoracoscopy. This minimally invasive procedure allows doctors to view the patient’s chest through a small camera and collect a tissue sample, also known as a biopsy. A pathologist examines the biopsy under a microscope to confirm the diagnosis and distinguish cancer’s cell type.
Peritoneal Mesothelioma
Peritoneal mesothelioma is one of the four primary types of malignant mesothelioma. The name stems from the area where cancer develops, along with the peritoneum, also known as the lining of the abdomen. Roughly 250 to 500 new cases of peritoneal mesothelioma are diagnosed in the U.S. each year, making it the second-most common mesothelioma type.
The peritoneum is a protective membrane that surrounds the abdomen, or belly. It has two layers, and mesothelioma can develop on both. The parietal layer covers the abdominal cavity, while the visceral layer surrounds the stomach, liver and other organs of the abdomen. Together, the layers support the abdominal cavity as a whole and the organs within it.
- Less than 20% of all cases
- Develops on lining surrounding the abdomen
- Responds best to a combination of surgery and heated chemotherapy
- Symptoms: Abdominal pain or swelling, bowel obstruction, diarrhea or constipation
Peritoneal Mesothelioma Causes
Although no definitive answer is available, cancer experts most commonly associate the cause of peritoneal mesothelioma with the following theories:
- Swallowed asbestos fibers travel from the digestive system to the peritoneum.
- Inhaled asbestos fibers reach the peritoneum through the lymphatic system, which produces and stores cells that fight disease.
Peritoneal Mesothelioma Symptoms
You may not experience cancer symptoms for 20 to 50 years after your first exposure to asbestos. Once asbestos fibers reach the peritoneum and irritate the cells, the peritoneal lining starts to thicken. As cancer develops, the buildup of excess fluid in the abdomen, known as ascites, may occur next. Over time, tumors form and place pressure on the organs.
Peritoneal Mesothelioma Diagnosis
Peritoneal mesothelioma accounts for 10-20 percent of all diagnosed cases. The latest advances in medical technology allow doctors to diagnose this disease earlier than ever before, yet even experienced cancer doctors can struggle to diagnose it accurately. In fact, the process can take months.
The process of diagnosing peritoneal mesothelioma is similar to that of other mesothelioma types. It starts with a thorough examination of your medical history, occupational history, and overall physical condition, followed by a series of tests including imaging scans and biopsies.
Be sure to mention any history of asbestos exposure, even if your doctors forget to ask. It’s important to share every detail you can remember, including the dates the incidents occurred and the length and duration of the exposures. This information will alert your doctors about the possibility of an asbestos-related disease and help them determine the appropriate next steps.
Because this cancer is so rare, doctors who lack experience with the disease often misdiagnose mesothelioma patients with more common illnesses. This serious mistake delays proper treatment. Peritoneal mesothelioma symptoms like abdominal swelling, weight loss and hernia also arise in other abdominal cancers and many less serious conditions, increasing the likelihood of a misdiagnosis.
If you have a history of asbestos exposure, the best way to ensure an accurate diagnosis is to schedule an appointment with a specialist. Doctors who specialize in mesothelioma and other asbestos-related conditions have the knowledge and tools needed to make a prompt diagnosis and explain all the treatment options available to you.
Pericardial Mesothelioma
Pericardial mesothelioma develops in the thin membrane surrounding the heart, known as the pericardium. Surgery and chemotherapy can help people live longer with cancer and other therapies can control symptoms such as pericardial effusion.
- Rarest type
- Forms on soft tissue around the heart
- Best treated with a multimodal approach (combination of treatments)
- Symptoms: Heart palpitations, chest pain, murmurs
Most pericardial mesothelioma patients experience no symptoms when cancer initially develops, a fact that contributes to a late-stage diagnosis. The symptoms also resemble those of other heart conditions, making cancer difficult to accurately diagnose. Fluid buildup around the heart can thicken the pericardial layers. This causes symptoms.
Pericardial Mesothelioma Causes
The causal relationship between asbestos exposure and this type of mesothelioma is not fully understood. Researchers confirm the pleural and peritoneal types are primarily caused by exposure to asbestos, yet the causes of the pericardial type are less definitive.
A 2017 review of medical literature on pericardial mesothelioma reported asbestos exposure in 25% of cases. Another 2017 study published in the Annals of Epidemiology reported the majority of patients with pericardial mesothelioma have no history of asbestos exposure.
Pericardial Mesothelioma Symptoms
Most symptoms are caused by the buildup of fluid and the thickening of pericardial layers. The presence of any of these symptoms should be followed by a visit to the doctor with recommended screenings such as an X-ray or CT scan. If you are experiencing any of these symptoms, especially heart-related symptoms, schedule an appointment with your doctor immediately. Screening tests like X-rays, CT scans and echocardiograms can usually reveal the underlying cause of these health problems.
Pericardial Mesothelioma Diagnosis
To diagnose pericardial mesothelioma, doctors make a cumulative assessment of your symptoms, medical history, and current medical condition. Next, you will receive a physical examination, imaging tests and biopsy to determine the location of tumors and confirm whether or not they are cancerous.
Researchers think pericardial mesothelioma occurs when asbestos lodges itself around the heart. When you see a doctor to discuss heart-related symptoms, one of the first diagnostic tests you will receive is an echocardiogram, which is essentially an ultrasound for your heart. This noninvasive test uses sound waves to help doctors see the size and shape of your heart and determine how well it is working overall.
Although an echocardiogram can reveal fluid buildup around the heart and help guide pericardiocentesis, the procedure doctors perform to drain the fluid, other imaging scans are needed to determine if potential tumors are present. If doctors spot abnormal growths, they need to take a fluid or tissue sample and perform a biopsy, which can confirm a mesothelioma diagnosis.
These tumors generally are not localized, and they tend to cover most of the heart. Furthermore, this cancer type accounts for approximately half of all pericardial tumors.