Pericardial Mesothelioma: Causes, Diagnosis and Prognosis

• 1 Pericardial mesothelioma is the rarest form of asbestos-related cancer.
• 2 Tumors first form in the lining of the heart (pericardium).
• 3 Pericardial mesothelioma is often not diagnosed until an autopsy is performed.
• 4 Despite the worst prognosis, there are several treatment options.

Pericardial mesothelioma is an extremely rare form of the disease, accounting for only 1–2% of all mesothelioma diagnoses. Pericardial mesothelioma occurs in the pericardium, the two-layer membrane that lines the heart. In some cases, the cancers were secondary tumours caused by other forms of mesothelioma and other metastatic cancers.

Because it is the rarest form of mesothelioma, research has been limited, making diagnosis difficult and limiting treatment options.

Pericardial mesothelioma

• CAUSE // Inhalation or ingestion of asbestos
• LOCATION // The lining of the heart (pericardium)
• GENERAL SYMPTOMS // Chest pain
• Pericardial effusion (fluid accumulation)
• Arrhythmia
• CARE // Surgery
• Chemotherapy
• FORECAST // 6 months

What Causes Pericardial Mesothelioma?

Researchers aren’t so sure this rare form of mesothelioma is closely related to asbestos exposure, even though most cases can be attributed to asbestos exposure. A recent study that followed 103 cases of pericardial mesothelioma between 2000 and 2016 found that only 25% of patients had a history of asbestos exposure.

Some researchers argue that the most common cause of pericarditis is metastasis, with several studies stating that primary pericardial is extremely rare and may even be benign. Some studies have observed tumors due to either primary pleural mesotheliomaorperitoneal mesothelioma. This is in addition to other cancers such as lung cancer, leukemia, breast cancer, or melanoma.

As for cases that may be associated with asbestos, researchers are still not sure how asbestos fibers reach the pericardium. Forensic experts noted asbestos fibers found in the pericardium in some autopsy reports. However, there is not enough evidence to determine how the mineral was able to enter the heart.

Diagnosis Of Symptoms Of Pericardial Mesothelioma

Tumors of pericardial mesothelioma develop between two layers of the mesothelium. Studies have shown that the tissue first begins to scar and thicken, which limits the movement of the heart muscle. Some patients may also have a pericardial effusion, where fluid accumulates around the heart and further impairs its function.

Because these tumors are very dangerous, patients often experience severe symptoms before the disease progresses to advanced stages. In some cases, however, patients may not experience symptoms before cancer kills them due to the long latency period. This is due to how quickly heart function becomes impeded by aggressive mesothelioma tumors.

Symptoms Of Pericardial Mesothelioma

• Chest pain
• Shortness of breath (difficulty, laboured breathing)
• Lethargy
• Pericardial effusion
• Tachycardia (abnormal, rapid heartbeat)
• Cardiac tamponade (compression of the heart with excess fluid)
• Murmurs in the heart
• Arrhythmias (irregular heartbeat)
• Tachycardia (abnormal, rapid heartbeat)
• Constrictive pericarditis (chronic inflammation of the pericardium)
• Visible jugular vein pulse
• Hypotension (low blood pressure)
• Heart failure

As with other forms ofmesothelioma cancer symptomsare nonspecific and can worsen rapidly due to the aggressive nature of cancer, making an accurate differential diagnosis difficult. This is possibly the most aggressive form of mesothelioma due to its location. Unfortunately, many patients do not get a proper diagnosis until a post-mortem autopsy is performed.

However, intravital diagnosis is not entirely impossible, as recent studies have explored newdiagnostic techniques that may help differentiate pericardial mesothelioma from other cardiac tumors and diseases. Reports have shown that pericardial mesothelioma can be mistaken for other cancers such as adenocarcinomas, angiosarcomas, lymphomas, and carcinomas. It has also been misdiagnosed as non-cancerous conditions, including heart disease, tuberculous pericarditis, and lupus.

As with other forms of malignant mesothelioma and cancer, imaging studies are usually the first step in diagnosing. Abnormalities in the chest cavity, such as pericardial effusions or visible tumors, are usually first detected on an X-ray or CT scan. A chest CT or PET scan can show any tumours around the heart or fluid accumulation in more detail and accuracy, which can help make the correct diagnosis.

A biopsy is the only way to confirm the diagnosis definitively. Doctors may take a tissue sample or a sample of the pericardial effusion for analysis. In addition topathological tests, which include histology (determining cell types) and cytology (how mesothelioma cells function and spread), doctors also often need to undergo an immunohistochemistry process to confirm a diagnosis.

Immunohistochemistry is a type of staining that uses specific antibodies to target specific antigens or proteins in a sample that can help identify mesotheliomas, such as cytokeratin, WT-1 protein, and other mesothelial markers. The antibodies will bind to these antigens, which can be viewed under a microscope. Mesothelioma biomarkers, such as calretinin and mesothelin, help make a correct diagnosis.

Stages Of Pericardial Mesothelioma

Like peritoneal mesothelioma, pericardial mesothelioma does not have a clear staging system due to its rarity. Also, because the cancer is so aggressive, many patients are not diagnosed until the cancer is post-mortem or when cancer becomes more common with limited treatment options.

Although there is no specific staging system for pericardial mesothelioma, researchers can determine how far cancer has progressed based on more general characteristics.

Stages Of Pericardial Mesothelioma

• Stage 1: Mesothelioma is localized without metastases. Patients with mesothelioma have more treatment options, including curative surgery. Patients diagnosed at this stage have the most favourable prognosis.
• Stage 2: The cancer is still localized but may have metastasized to nearby tissues, organs or lymph nodes. Patients still have definitive treatment options, including surgery, depending on how much and where cancer may have spread.
• Stage 3: Mesothelioma has a more distant distribution to an area outside the original tumor, although it is still localized to one side of the body. The cancer cells have also spread to the lymph nodes. At this stage, treatment options may be limited to palliative care.
• Stage 4: Cancer cells have spread distantly to both sides of the body. Because of such severe progression, surgery is not an option, and patients can only receive palliative treatments to relieve symptoms and improve their quality of life.

Because so few cases have been reported, experts are not clear on how pericardial mesothelioma can develop in the body. Some case reports note that mesothelioma cells can spread throughout the heart and pulmonary artery, which can help cancer spread anywhere in the body to more distant organs. However, many studies classify pericardial mesothelioma tumors as secondary or metastatic tumors.

In several of these studies, the researchers identified some common organs that metastatic pericardial mesothelioma could reach.

Sites Of Metastasis Of Pericardial Mesothelioma

• Liver
• Rib cage
• Abdomen
• Lungs
• Lymphatic system

Pericardial Mesothelioma Prognosis

Patients with malignant pericardial mesothelioma face the poorest prognosis of all three types. Detecting this form of asbestos cancer has proven to be especially difficult. Researchers are still unsure about the most effective treatment options that can increase life expectancy.

One recent study showed that the average life expectancy is only 5.6 months in 103 cases of pericardial mesothelioma. Some case reports have documented survival as short as a few weeks after diagnosis, even in a clinical study of a patient who managed to remove the tumor.

In addition to the location of the disease, the stage, cell type of mesothelioma, age, gender, and general health of the patient are just some of the factors that can affect the prognosis and the treatments available.

Treatment Of Pericardial Mesothelioma

Treatment options for pericardial mesothelioma are limited as there have been too few cases for researchers to understand the most effective treatment or combination of treatments. Clinical trials for pericardial mesothelioma are also almost non-existent for the same reason, although researchers may use new treatments that have shown success in similar cancers.

In reported cases, physicians have largely relied on the conventional treatments of surgery, chemotherapy, and radiation therapy for patients with pericardial mesothelioma. In a few rare cases, patients have been able to undergo surgery to remove or shrink localized tumors in a curative or palliative manner. Specialists can provide multiple types of mesothelioma surgery for their patients.

Surgical Options for Pericardial Mesothelioma

Percutaneous Balloon Pericardiotomy/Pericardial Window

This surgical procedure, sometimes called PBP, also helps to remove pericardial effusions. A long, thin tube is inserted into the pericardium and uses a balloon to separate thin layers of membrane, allowing excess fluid to drain and preventing future fluid accumulation. More invasive drainage procedures, such as a pericardial window (creating a surgical opening in the pericardium), may be needed to reduce fluid pressure on the heart.

Pericardiectomy

This operation, called pericardial removal, removes part or all of the pericardium. The goal is to remove any visible tumors and, hopefully, many cancer cells to prevent the disease from growing and spreading. Since this is a major cardiac procedure, it is only an option for patients with an earlier diagnosis and better overall health to withstand invasive surgery.

Pericardiocentesis

This procedure removes excess fluid from the pericardium to relieve pressure on the heart and improve its function. While not considered curative, pericardiocentesis can significantly improve quality of life by relieving symptoms.

Percutaneous Balloon Pericardiotomy/Pericardial Window

Sometimes referred to as PBP, this surgical procedure also helps remove pericardial effusions. A long, thin tube is inserted into the pericardium and uses a balloon to separate the thin layers of the membrane. This allows the excess fluid to drain and helps prevent future fluid buildup. More invasive drainage procedures, such as a pericardial window (creating a surgical opening in the pericardium), may be needed to relieve the pressure of the fluid on the heart.

Pericardiectomy

This surgery sometimes referred to as pericardial stripping, removes part or all of the pericardium. The intent is to remove any visible tumors and, hopefully, many cancerous cells to prevent the growth and spread of the disease. It is only available to patients diagnosed early and in reasonable health to withstand the aggressive procedure.

Pericardiocentesis

This procedure removes excess fluid in the pericardium to relieve pressure on the heart and improve functionality. While not considered curative, pericardiocentesis can greatly improve quality of life by alleviating symptoms.

In addition to surgery, standard chemotherapy with pemetrexed and cisplatin has also been used in some cases to reduce tumor mass and relieve symptoms. In a 2017 review of over 100 cases of pericardial mesothelioma, researchers noted that 37% of patients received combination chemotherapy with increased survival.

Radiation therapy has also been used but has not shown any evidence of effective treatment or slowing the spread of the disease. It may help some patients as a palliative procedure to relieve some of the symptoms.

Again, clinical trials for this form of mesothelioma are limited due to the rarity of cancer. However, researchers are working on testing the efficacy of other promising treatments for pericardial mesotheliomas, such as immunotherapy and photodynamic therapy.