Cardiac tumors (cardiac neoplasms)Cardiac tumors may be primary (benign or malignant) or metastatic (these are always malignant and are far more common than primary tumors). Signs and symptoms are nonspecific and highly variable depending on the localization, size, and composition of the cardiac neoplasm. The first imaging modality alerting the clinician to the presence of a cardiac mass usually is echocardiography, most often performed for another indication.
Primary tumors of the heartPrimary cardiac tumors are rare. They are much rarer than metastatic ones. Most primary cardiac tumors are benign (75-80%). The most common type of primary benign cardiac tumor is myxoma (followed by lipoma and fibroelastoma).
Primary malignant cardiac tumors are extremely rare and they are almost all sarcomas, with angiosarcoma being the most common among them (Lymphomas and malignant paragangliomas are even more rare types of primary cardiac malignancies). Sarcomas can occur in any chamber of the heart but they are more frequently located in the right or left atrium. Malignant cardiac tumors have a poor prognosis.
In childhood, primary cardiac tumors are extremely rare and mainly include rhabdomyoma and fibroma. Rhabdomyomas are the most common cardiac tumors in childhood. Cardiac rhabdomyomas are benign tumors that originate from cardiac myocytes. Some cases are sporadic and isolated, but in 50% of cases, they are associated with tuberous sclerosis. The most common malignant cardiac tumor in childhood is rhabdomyosarcoma. Cardiac tumors in children are often associated with genetic syndromes.
The perioperative mortality is about 8% overall but for myxoma, which is the most common cardiac tumor resected, the perioperative mortality is much lower, approximately 1% .
Metastatic cardiac tumorsMetastatic cardiac tumors are far more frequent (approximately 30- 40 times more frequent) than primary tumors of the heart. Neoplasms that may involve the heart are mainly melanomas, lymphomas, lung, breast, and renal cancer.
Metastases to the heart can occur by the following three mechanisms:
- Direct extension of a neoplasm via adjacent tissues
- Dissemination of cancer cells in the blood or the lymphatic system
- Propagation through the superior or the inferior vena cava to the right atrium.
Echocardiography is the most commonly used imaging method in suspected cardiac metastatic disease, but magnetic resonance imaging and computed tomography are also valuable. Metastatic tumors affecting the myocardium, usually appear as distinct, brightly echogenic masses. Rarely, metastatic tumors may seed the endocardium and echocardiographically appear as intracavitary masses.
Cardiac metastases are clinically apparent only in 10% of the cases, and usually, they are not the cause of the patient's presenting symptom, although in some cases they cause symptoms (dyspnea due to heart failure, or due to a large pericardial effusion, chest pain due to pericarditis, signs of cardiac tamponade, arrhythmias, syncope due to atrioventricular block, etc). They usually occur in the setting of a previously diagnosed malignant neoplasm ( almost always a widespread primary neoplasm). The differential diagnosis of a cardiac manifestation in a patient with cancer includes cardiotoxicity because of chemotherapy or occurrence of cardiac metastases.
The general prognosis of patients with cardiac metastases is poor. For patients with intramyocardial metastasis, survival generally is limited to a few months at most. Survival is longer for intracavitary tumors. Occasional patients have survived several years.
Symptoms and clinical findings of cardiac neoplasmatic disease
Myxomas, as well as other primary cardiac tumors, may present with one or more of a classic triad of manifestations which includes sequelae of valvular obstruction, embolic phenomena and constitutional symptoms.
Manifestations of heart failure are common in case of large intracavitary tumors causing obstruction to blood flow. Depending on the heart chamber involved, the resulting manifestations may be of :
- congestive (backward) heart failure, such as dyspnea, peripheral edema, or
- low cardiac output (forward) heart failure, such as fatigue, or hypotension.
Intracardiac (intracavitary) tumors, if they are large enough, cause clinical manifestations due to the obstruction of blood flow. Myxomas of the left atrium may prolapse via the mitral valve, causing symptoms of mitral obstruction (dyspnea, syncope depending on a change of patient's position, etc.). Tumors of the right heart chambers may manifest with signs and symptoms of right-sided heart failure. Primary malignant cardiac tumors can also cause congestive heart failure when there is extensive myocardial involvement.
Constitutional symptoms (fever, chills, fatigue, malaise, weight loss, Raynaud phenomenon), as well as some laboratory findings (elevated erythrocyte sedimentation rate, anemia, polycythemia, leucocytosis, thrombocytosis, thrombocytopenia), result from substances secreted by the tumor or released due to tumor necrosis.
The constitutional symptoms, signs and laboratory findings may resemble the findings of vasculitis or autoimmune connective tissue disease.
Embolism due to a cardiac tumor can in many cases be the first manifestation. An embolism can manifest as a pulmonary embolism or more commonly as a peripheral embolism (e.g a stroke or acute ischemia of an extremity or a digit), depending on the location of the tumor in a right or left heart chamber, respectively. The embolus consists either of tumor cells or of thrombi formed on the tumor surface.
Atrial or ventricular arrhythmias or atrioventricular block can occur as a result of tumor infiltration of the myocardium or the conductive pathways of the heart. This is particularly true for fibromas (these are intramural tumors, located in the left ventricle, mainly in the interventricular septum). In some cases, sudden cardiac death is the first manifestation of a cardiac tumor.
The clinical examination is nonspecific in cardiac tumors. However, cardiac symptoms and signs in a patient who has had no previous cardiac disease, in association with general symptoms and embolic events, should initiate cardiac investigations.
Diagnosis of cardiac tumorsWhenever a cardiac mass is encountered on echocardiography, the differential diagnosis includes a thrombus, a vegetation or a tumor, with the first two being much more common in comparison with a tumor. To reach a conclusion the physician should focus on:
- the clinical context and presentation
- the location
- the imaging characteristics
- the findings of additional imaging tests (when necessary), such as CT or MRI
- in case of a tumor the definitive diagnosis is by biopsy (histological examination), although imaging is in many cases suggestive of the correct diagnosis.
Differential diagnosis of an intracavitary cardiac tumor includes an intracavitary thrombus. Contrast injection can be helpful in the differential diagnosis because it will intensify the signals from tumors, but not from thrombi.
If echocardiographic findings cannot suggest the diagnosis, further imaging procedures such as computed tomography (CT) or magnetic resonance imaging are employed. Magnetic resonance imaging (MRI) provides the best spatial resolution and allows exact localization of the tumor. It may also differentiate fat from a thrombus or tumor. It provides particularly valuable information for intramyocardial and malignant tumors.
In differentiating between benign and malignant neoplasms, a useful test is18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT). If there is a decision to proceed with cardiac tumor surgery (surgical excision of the tumor under cardiopulmonary by-pass), in the presence of risk factors for coronary heart disease, coronary angiography or CT coronary angiography should be performed, so that coronary stenoses can be bypassed during surgery for the tumor. Note that primary cardiac tumors should be totally resected whenever possible.
A woman 55 years old with a history of diabetes and hypertension. The ECG showed sinus rhythm with mild nonspecific T wave inversion. Recently she suffered an ischemic stroke with mild left hemiparesis. A 5-chamber apical echocardiographic view of this patient is shown below. Please name the structures 1-5. What has probably caused the ischemic stroke and which is the proposed management ?
1. Left ventricle 2. Mitral valve 3 A mass in the left atrium, with an appearance which is highly suggestive of a tumor (with a myxoma being by far the most probable diagnosis). A thrombus could be considered in the differential diagnosis, but in this case, it is not likely since there is a left atrium of normal size, and there was no history of atrial fibrillation or of mitral stenosis (conditions that can lead to the formation of a left atrial thrombus). Also, the position and size of the mass are clearly more suggestive of a tumor than of a thrombus. 4. Left atrium 5. Aorta.
The patient was managed with a successful surgical resection of the tumor. Biopsy has proven that it was a myxoma.
When a familial myxoma syndrome is identified or suspected, screening first-degree relatives with echocardiography is mandatory.
On echocardiography, a myxoma has the appearance of a heterogeneous mobile mass, often globular, usually with a smooth or lobulated surface, 4-8 cm in diameter, attached to the endocardial surface (usually the interatrial septum) with a narrow base (stalk or pedicle). Occasionally it is attached with a wide base. Their echogenicity is not homogeneous and they may include areas of echolucensy and in some cases calcifications. Polypoid myxomas are larger with a smooth surface and they include lucencies and cystic areas due to hemorrhage and necrosis. Papillary myxomas tend to be smaller and have multiple villi. This subtype is associated with embolic phenomena,
Other benign cardiac tumors: Lipoma / Papillary fibroelastoma (endocardial papilloma)
Lipomatous hypertrophy of the interatrial septum is a prominent thickening of the septum due to the accumulation of adipose tissue. The proximal and distal portions of the atrial septum appear thickened, generally with sparing of the fossa ovalis. Lipomatous hypertrophy of the interatrial septum is not a true tumor. It is more common in obese elderly women. It may be associated with supraventricular arrhythmias.
|Papillary fibroelastoma of the aortic valve|
Cardiac sacomaSarcomas are the most common malignant primary cardiac tumors. Typical age of presentation is between 40 and 50 years. On echocardiography, they appear as a broad-based mass with heterogeneous echogenicity, usually in the right atrium. They may also appear in any cardiac chamber and they also often affect the pericardium, resulting in a pericardial effusion and pericardial chest pain. When located in a right cardiac chamber they can affect tricuspid valve function, produce clinical manifestations of right-sided heart failure and /or metastasize to the lungs. Hypoechogenic areas may indicate tumor necrosis. Differential diagnosis is with a myxoma. In contrast to a myxoma, sarcomas do not have a stalk. Sarcomas tend to have a rapid growth, obstructing blood flow. Treatment with surgical debulking of the tumor is occasionally performed.
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