What is a cardiac tumor?
Primary cardiac tumors are extremely rare, with an incidence of less than 0.1%. They are benign or malignant neoplasms that originate from the internal cardiac lining tissues, the muscle layer or the pericardium.
Secondary or metastatic cardiac tumors, on the other hand, are always malignant, more common than malignant primaries, and have spread from elsewhere in the body to the heart. Most commonly they have been primary in the lung, breast, kidney, soft tissue (sarcomas), blood (leukemias), lymphatic tissue (lymphomas), or skin (melanomas). Cancers that affect the thorax, such as lung or breast cancer, can reach the heart by direct invasion, often into the membrane that surrounds the heart (the pericardium). Other cancers can also reach the heart muscle through the bloodstream or the lymphatic system.
The smallest proportion of cardiac tumors is malignant: 25%, while 75% of cases are benign cardiac tumors.
Subtypes of benign primary cardiac tumors
- Myxoma – is the most common, responsible for 50% of all primary cardiac tumors. It is two to four times more common in women than in men. Approximately 75% of myxomas arise in the left atrium, and the rest occur in other heart chambers, either as a solitary tumor or (less frequently) at multiple areas. Its diameter can be up to 15 cm³ and the cell that can give rise to it is unknown;
- Papillary fibroelastoma – these are avascular papillomas that occur in the heart valves in more than 80% of cases and are more frequent on the left side of the heart;
- Rhabdomyoma – the most common heart tumor in infants and children, accounting for 60% of cases. They are usually multiple tumors. There is a very close relationship between rhabdomyomas and tuberous sclerosis: sclerosis is reported in up to 80% of the cases of patients with this tumor, and the tumor is detected in up to 72% of the cases of patients who had previously been diagnosed with tuberous sclerosis;
- Fibroma – is also more frequent in children and is usually a solitary tumor. Its diameter can reach up to 10 cm;
- Hemangioma – extremely rare, with a diameter of 2 to 4 cm and can regress spontaneously, although in children its evolution can be unfavorable;
- Lipoma – exclusive to adults, but in a very wide age range. It can evolve to trigger arrhythmias.
Subtypes of primary malignant cardiac tumors
- Angiosarcoma – a tumor that occurs predominantly in males and is located mainly in the right atrium (80% of cases). It can cause metastases to the pleura, mediastinum and lungs;
- Rhabdomyosarcoma – manifests in adult males, originates in the striated muscle and affects any of the cardiac chambers;
- Pericardial mesothelioma – rare, affects all age groups, more commonly men than women. It can send metastases to spine, adjacent soft tissues and brain;
- Lymphoma – extremely rare, usually occurs in patients with HIV or other diseases leading to immunodeficiency.
Subtypes of metastatic heart tumors (malignant)
- Melanoma – the reason is unknown, but melanoma has a predilection for cardiac metastasis: half of all cases of melanoma disseminated throughout the body show deposits in cardiac tissue in autopsy findings;
- Lung and breast carcinoma – these are the most common sources of metastasis to the heart, and can spread to the pericardium and cause pericardial effusions;
- Leukemia – when a leukemia metastasis happens, it is usually to the heart, silent and sometimes with large deposits and hemorrhagic pericardial effusion;
- Lymphoma – also has the metastasis usually directed to the heart in an asymptomatic way, forming small intramyocardial masses.
Symptoms and signs of heart tumor
The symptoms of malignant cardiac tumors are essentially the same as those of benign cardiac tumors, with the malignant ones tending to get worse more quickly since they grow faster.
In general, symptoms include:
- Sudden development of heart failure (with shortness of breath and fatigue);
- Cardiac arrhythmia (causing palpitations, weakness, or fainting)
- Bleeding and fluid buildup in the pericardium (which can interfere with heart function and cause cardiac tamponade).
In metastatic heart tumors, symptoms of the original tumor and the metastases occur in parallel. For example, lung cancer that has metastasized to the heart can have symptoms such as difficulty breathing, fatigue, and coughing up blood.
The more specific symptoms depend on the type of tumor, its location, size and fragility.
Diagnosis of a cardiac tumor
When symptoms raise the suspicion of a medical specialist, the diagnosis of cardiac tumors is made by imaging tests: echocardiography, MRI, and CT scan.
Echocardiography is the test that confirms the diagnosis. TEE (transesophageal echocardiography) is best for visualizing atrial tumors, while transthoracic echocardiography works best for detecting ventricular tumors.
Cardiac MRI is used to identify the characteristics of tumor tissues and thus find clues about the type of tumor.
Contrast-enhanced cardiac CT scans, on the other hand, can provide detailed information with superior spatial resolution.
A biopsy is not usually carried on cardiac tumors because imaging tests can differentiate benign from malignant tumors. Furthermore, in a cardiac tumor biopsy there is a risk of unintentional dissemination of neoplastic cells in patients with a malignant primary tumor. On suspicion of primary tumor, surgery is preferred over biopsy.
For metastatic cardiac tumors, additional tests are carried out to find the original cancer (unless its location is already known).
Treatment of cardiac tumors
Benign primary cardiac tumors are usually treated by surgical excision – the procedure is only not performed if another disease contraindicates surgery. The exception is rhabdomyoma, which mostly regresses spontaneously and requires no treatment.
The treatment for primary malignant cardiac tumors is usually palliative (radiotherapy, chemotherapy, and care for complications, for example), since the prognosis is reserved, that means, the probability of improvement or cure is small.
For metastatic cardiac tumors, treatment depends on the origin and type of tumor. It may include systemic chemotherapy or palliative therapy, and the prognosis is also reserved.
Cardiac tumor prevention
Because there are no risk factors associated with cardiac tumors, it is not possible to prevent their development.