Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
Tumors Affecting the Cardiovascular System
Additional content is available online at Elsevier eBooks for Practicing Clinicians
Cardiac masses frequently present significant diagnostic and therapeutic clinical challenges. In many cases, a cardiac mass is detected as an incidental finding and the resultant evaluation may culminate in the confirmation of a cardiac tumor; however, this is generally an uncommon event since other cardiac masses, including normal structures (particularly within the right atrium), thrombi, or valvular vegetations are more common. , This chapter describes the initial symptoms and signs that may indicate a cardiac tumor, followed by an explanation that often includes cardiovascular imaging. Once a cardiac tumor is suspected, the ultimate diagnosis is usually confirmed by a biopsy or surgery as histologic diagnosis has a direct bearing on further treatment planning. The remainder of the chapter focuses on the delineation and potential management of cardiac tumors as well as the overall anticipated outcomes. In many cases, the final pathologic diagnosis is typically confirmed by surgical removal after many difficult decisions regarding investigations and treatment are made in relation to the urgency of the clinical situation and initial presentation.
Clinical Manifestation of Cardiac Tumors
Initial Clinical Decision Making Regarding Cardiac Masses
Patients with cardiac tumors may present with no symptoms or physical findings and receive notification of an abnormality on an imaging examination performed for an unrelated indication. Alternatively, patients may experience nonspecific or detailed symptoms or signs that should alert practitioners to the possibility of a cardiac tumor ( Table 98.1 ). The most important consideration in confirming the presence of a cardiac tumor is a high index of suspicion and the integration of symptoms, physical findings, and imaging characteristics in a logical manner to establish a clinically reasonable plan of action. The initial diagnostic test for a patient with concerning symptoms often involves an imaging test ( Table 98.2 ), such as two-dimensional (2D) echocardiography (2D-echo) (see Chapter 16 ) or cardiac magnetic resonance imaging (cMRI) (see Chapter 19 ). Depending on the characteristics of this mass and the known comorbidities of the patient, additional imaging may be undertaken. These including three-dimensional (3D) echo with or without contrast (see Chapter 16 ), cMRI with gadolinium (see Chapter 19 ), coronary angiography (to define the presence of coronary artery disease) (see Chapter 21 ), positron emission testing (PET) to provide staging for cancer (see Chapter 18 ), or computed tomography (CT) (see Chapter 20 ), including a CT angiogram (CTA) to clarify intrathoracic structures. , Transesophageal echocardiography (TEE) can also provide very specific anatomical information that is critical to treatment planning (see Chapter 16 ).
Clinical Scenarios When Evaluating a Cardiac Mass
In assessing a cardiac mass as the initial evaluation for a cardiac tumor, the clinical context in which the image was obtained is critical for making a diagnosis. A differential diagnosis of a cardiac mass is broad and includes tumors, thrombi, infection, and artifacts ( Table 98.3 ). The most important characteristic would be evidence of perfusion into the mass as an indicator of a benign or malignant tumor. When considering typically encountered clinical scenarios, a patient with new-onset heart failure and severe left ventricular (LV) dysfunction, who has a 2D-echo image that shows an apical mass, a cardiac tumor is quite unlikely. This suspicion would be firmly established if there was a severe wall motion abnormality in that region, the mass appeared distinct from the myocardial wall and was lobulated ( Fig. 98.1 ). An LV mass with these characteristics is much more likely to be a thrombus as opposed to a tumor. Additionally, patients treated for cancer with indwelling catheters may experience development of abnormal masses, which may be observed during routine screening for cardiac dysfunction. As shown in Figure 98.2 , this right atrial mass seen during transthoracic echocardiogram and then characterized more completely with cardiovascular MRI is consistent with a thrombus.
TABLE 98.3
Differential Diagnosis of Cardiac Masses
|
Another scenario involves a patient with a history of melanoma that is metastatic to other organs, who has routine cardiac imaging and a solid mass is seen in an unusual location. Since there is no wall motion abnormality and no significant valvular disease or clinical signs suggestive of infective endocarditis, a mobile mass on the tricuspid valve is very likely to be a metastatic lesion to the heart ( Fig. 98.3 ). Another imaging characteristic that provides insight indicating a tumor is present is the behavior of the mass during cardiac motion. If a tumor is infiltrating the myocardium, it is unlikely to contract in a normal fashion. An LV myocardial apical mass contracting similarly to the surrounding tissue is likely to be either focal hypertrophy ( Fig. 98.4 ) or LV noncompaction ( Fig. 98.5 ) , as opposed to a cardiac tumor. Furthermore, progression of an image over time also may indicate the pathologic process. If a cardiac mass changes in size during serial imaging, suspicion of a cardiac tumor is much higher ( eFig. 98.1 ). However, an LV apical mass that is stable for months or years is unlikely to be a malignant cardiac tumor as noted in Figures 98.4 and 98.5 .
The exact nature and location of a mass is critical in the determination of the likelihood that it is a tumor. A classic example of this principle is lipomatous hypertrophy of the intraatrial septum ( Fig. 98.6 ). The initial suspicion might be that this is a myxoma or other tumor, but an MRI with specific characteristics that are a hallmark for lipomatous hypertrophy will confirm the diagnosis. Additionally, ridges of tissue including the crista terminalis or the eustachian valve remnant can also mimic cardiac masses ( eFig. 98.2 ).
TABLE 98.1
Range of Clinical Findings That May Indicate a Cardiac Tumor
|
TABLE 98.2
Common Testing That May Indicate the Possibility of a Cardiac Tumor
|
Classification of Cardiac Tumors
Cardiac tumors are divided into primary and secondary tumors. Primary cardiac tumors are very rare, with an autopsy incidence of 1:2000. These tumors include benign or malignant neoplasms that may arise from any tissue of the heart. In terms of primary tumors, approximately 80% are benign and these can be grouped as simple or complex, considering the treatment that is typically required. The approximately 20% of primary cardiac tumors remaining are malignant and usually are pathologically described as sarcomas. Table 98.4 summarizes some of the pathologic descriptions of cardiac tumors that have been reported, albeit not an exhaustive list, since there have been many very specific pathologic descriptions and it can be difficult to adequately categorize them. Thus, general categories will be discussed in the remainder of this chapter. Figure 98.7 illustrates the types of tumor that may affect different chambers of the heart and pericardium. Secondary or metastatic cardiac tumors are 30 times more common than a primary neoplasm with an autopsy incidence of 1.7% to 14% or 1:100.
TABLE 98.4
Pathologic Description of Cardiac Tumors
Benign
Malignant
Metastatic
|
Benign (Nonmalignant) Primary Cardiac Tumors
The majority (>80%) of the primary cardiac tumors are nonmalignant; however, because of their location these frequently require surgical treatment. , Myxoma constitutes about 50% of all benign cardiac tumors in adults, but only a small percentage of such tumors in children. Rhabdomyomas are the most common benign tumor in children and account for 40% to 60% of the pediatric cases. Other benign cardiac tumors that have been described include fibromas, lipomas, hemangiomas, papillary fibroelastomas, cystic tumors of the AV node, and paragangliomas.
Simple Benign Tumors
Myxomas
Most myxomas (>80%) are most commonly found in the left atrium and in decreasing frequencies in the right atrium, right ventricle, and left ventricle ( Fig. 98.8 ). , The incidence of cardiac myxoma peaks at 40 to 60 years of age, with a female to male ratio of approximately 3:1. Most myxomas occur sporadically but may be familial and occasionally these have been described in relation to a particular syndrome called Carney’s complex, an autosomal-dominant condition associated with cardiac myxomas, myxomas in other regions (cutaneous or mammary), hyperpigmented skin lesions, hyperactivity of the adrenal or testicular glands, and pituitary tumors. Carney’s complex occurs at a younger age and should be considered when cardiac myxomas are discovered in atypical locations in the heart.
Etiology and Pathophysiology
The exact origin of myxoma cells remains uncertain, but they are thought to arise from remnants of subendocardial cells or multipotential mesenchymal cells in the region of the fossa ovalis, which can differentiate along a variety of cell lines. The hypothesis is that cardiac myxoma originates from a pluripotential stem cell, and myxoma cells express a variety of antigens and other endothelial markers. Myxomas typically form a pedunculated mass with a short broad base (85% of myxomas), but sessile forms can also occur. Classically, myxomas appear yellowish, appear white or brownish, and are frequently friable. The tumor size can range from 1 cm to more than 10 cm, and the surface is smooth in the majority of the cases. A villous or papillary form of myxoma has been reported and contains a surface that consists of multiple fine or very fine villous, gelatinous, and fragile extensions that have a tendency to fragment spontaneously and are associated with embolic phenomena. Histologically, myxomas are composed of spindle and stellate shaped cells with myxoid stroma that may also contain endothelial cells, smooth muscle cells, and other elements surrounded within an acid mucopolysaccharide substance. Calcifications may also be seen in some cases.
Clinical Manifestations
Patients commonly are asymptomatic and the tumor is found as an incidental finding on 2D-echo. When symptoms are present, dyspnea, especially dyspnea that is worse while lying on the left side, should alert the astute clinician to the possibility of a myxoma. Most clinical presentations related to myxoma result from mitral valve obstruction (syncope, dyspnea, and pulmonary edema) followed by embolic manifestations. , Patients may present with nonspecific symptoms such as fatigue, cough, low-grade fever, arthralgia, myalgia, weight loss, erythematous rash, and laboratory findings of anemia and increased erythrocyte sedimentation rate (ESR), C-reactive protein, and gamma globulin levels. Less commonly they may have thrombocytopenia, clubbing, cyanosis, or Raynaud’s phenomenon. Physical exam findings can reveal a systolic murmur or a diastolic murmur suggestive of mitral stenosis. A tumor plop may potentially be heard (a low-pitched diastolic sound heard as the tumor prolapses into the left ventricle). , In one study, a cardiac auscultation abnormality was detected in 64% of patients, and the most common auscultation findings are a systolic murmur (in 50% of cases) followed by loud first heart sound (32%), an opening snap (26%), and a diastolic murmur (15%). The reason for the systolic murmur may be caused by damage to the valves, failure of the leaflets to coapt, or narrowing of the outflow tract by the tumor. A diastolic murmur is present due to obstruction of the mitral valve from the tumor. Tumor plop may be confused with a mitral opening snap or a third heart sound and can be detected in up to 15% of cases. Chest examination may reveal fine crepitations consistent with pulmonary edema while there may be peripheral signs of embolic phenomenon. The physical evidence of embolic phenomenon will vary depending on the vascular territory involved. Involvement of cerebral vessels results in neurologic signs; involvement of coronary arteries may result in an acute coronary syndrome; intestinal arterial obstruction may result in ischemic bowel; and peripheral arterial obstruction can result in limb-threatening ischemia.
Laboratory Testing
Laboratory test abnormalities may include anemia, elevated serum gamma globulin, elevated ESR, and elevated serum C-reactive protein, which is present in approximately 75% of the patients. There are no specific electrocardiogram (ECG) findings in myxoma. Chest x-ray findings are also nonspecific and include signs of congestive heart failure, cardiomegaly, and left atrial enlargement. In some cases, the tumor itself may be visible due to calcification. A 2D echo usually should demonstrate a mass in the atrium, with the stalk attached to the interatrial septum but myxomas have been reported in all chambers of the heart. A TEE provides specific delineation of the tumor including the size and origin. CT and MRI scans provide better delineation of the intracardiac mass, the extent of tumor in relation to extracardiac structures, and provide anatomical definition for preoperative planning ( Table 98.5 ).
TABLE 98.5
Imaging Characteristics of Tumors with Echo, CT, and cMRI
| Cardiac Tumor | Echocardiography (ECHO) | Computed Tomography (CT) | Magnetic Resonance Imaging (cMRI) |
|---|---|---|---|
| Myxoma | Mobile tumor | Narrow base of attachment | Mottled gadolinium contrast enhancement |
| Frequently attached fossa ovalis | Heterogeneous with low attenuation | Mobile on cine imaging | |
| Heterogeneous echogenicity | Possible calcification | Varying (mixture of values on T1 mapping) | |
| Papillary Fibroelastoma | Mobile valve leaflet mass | Mass seen on valve leaflets | Mobile mass on valve leaflets |
| Variable gadolinium contrast enhancement | |||
| Lipoma | General thickening of interatrial septum | Low attenuation due to fat | High T1 signal |
| Fat saturated images with low signal | |||
| Rhabdomyoma | Small lobulated hyperechoic intramuscular masses | Multiple masses with homogeneous signal intensity | |
| Uniform T1 and T2 values | |||
| Fibroma | Large intramural mass | Homogeneous with low attenuation | Uniform T1 and T2 values |
| Calcification may be present | Isointense on T1-weighted images | ||
| Large intramural mass | Large intramural mass | ||
| Hemangioma | Increased echogenicity | Heterogeneous with marked enhancement | Gadolinium enhancement present |
| Angiosarcoma | Invades across tissue boundaries | Invasive across tissue boundaries; low attenuation | Invasive across tissue boundaries |
| Varying or heterogeneous gadolinium enhancement | |||
| Pericardial effusion | Varying or heterogeneous T1 and T2 values | ||
| Lymphoma | Low echogenicity masses | Low attenuation masses | Enhancement with gadolinium that may be heterogeneous |
| Pericardial effusion | |||
| Metastases | Often multiple masses | Often multiple lesions | Often multiple lesions |
| May have pericardial effusion | Gadolinium enhancement |
Treatment
The only definitive treatment of cardiac myxoma is surgical removal. Generally, the myxoma is surgically excised using cardiopulmonary bypass and cardioplegic arrest. The tumor is removed by either right or left atriotomy or combined atriotomy, depending on the site and extent of the tumor. The choice of technique also depends on associated conditions that need surgical intervention, such as valve repair or replacement, and coronary disease if present. Lifelong follow-up is needed, as myxomas have some tendency to recur. The recurrence rate of myxoma has varied but one large experience suggests that is quite low and may be below 1%. ,
Fibroelastoma
Valvular structures may have a papillary fibroelastoma attached, which is often found incidentally. These are small in size, typically less than 2 cm, and most commonly occur on the aortic valve followed by the mitral valve. Rarely these may be found anywhere in the endocardial surface and the majority of fibroelastomas that have been reported are solitary, although multiple ones have been rarely reported. Fibroelastomas may result in embolic phenomena, and when situated on the aortic valve or the left ventricle, can cause coronary ostial occlusion ( Fig. 98.9 ). Grossly, they have a characteristic frond like appearance, resembling a sea anemone, and histologically the tumor has an inner central core of collagen surrounded by a layer of acid mucopolysaccharides and covered by endothelial cells ( eFig. 98.3 ). For the most part, complete surgical resection is recommended for left-sided papillary fibroelastoma primarily because of the high likelihood of systemic embolism, which can lead to stroke, myocardial infarction, peripheral embolism, and even sudden death. The decision for surgery in right-sided disease is more difficult as the number of asymptomatic right heart fibroelastomas is unknown and recommendation for surgery depends on the exact location, size, and potential risk to the patient. On imaging, especially echocardiographic imaging, there is a characteristic small, mobile, pedunculated, and very echo dense core that enables it to be differentiated from a vegetation or thrombi. Typically the structure of the valve can be preserved once the tumor is removed (see eFig. 98.3 ). The chance of recurrence appears low and there is no compelling data to continue anticoagulation long term unless there are other indications to do so.
Rhabdomyomas
Rhabdomyomas are usually found in the ventricle and are the most common benign cardiac tumor found in children. , The majority of these patients have signs of or a family history of tuberous sclerosis. In one study of patients with tuberous sclerosis complex, cardiac tumor was found in 48% of the patients, with an incidence of 66% in patients less than 2 years old. Frequently, these patients are asymptomatic although some patients with rhabdomyoma may present clinically with arrhythmias and heart failure. , It is possible these tumors may regress with age but can sometimes grow or appear during puberty. As a result of these uncertain outcomes, long-term clinical and echocardiographic follow-up is needed in patients with tuberous sclerosis. Most often, surgery can be avoided, although if arrhythmias become a symptomatic problem, antiarrhythmics and ultimately surgery may have to be considered.
Lipomas
A lipoma is a rare benign cardiac tumor comprising only 3% of all benign tumors. These tend to occur in the left ventricle or the right atrium but may be found anywhere in the heart as well as the pericardium. Although frequently asymptomatic, they may grow large enough to cause obstructive symptoms and require surgical intervention (see Fig. 98.6 ). Obstruction and compression of the superior vena cava may occur in patients with lipomas involving the right atrium.
Cystic Tumor of the AV Node (Previously Called Mesothelioma)
Because of their location near the atrioventricular node, these cystic tumors can present with varying degree of heart block or even sudden death. Cardiac MRI is particularly useful in the diagnosis of this tumor.
Other Very Rare Benign Cardiac Tumors
There are few very rare reports of hemangioma, , neurofibroma, teratomas, leiomyoma, and lymphangioma; however, there are not enough data to summarize expected findings. Typically these tumors will be diagnosed after resection. Complete resection of the tumor is possible in most of the benign primary tumors, compared with malignant tumors, with a perioperative death of 1.4%. Hemangiomas are characteristically vascular and maybe endocardial or epicardial ( Fig. 98.10 and eFig. 98.4 ).
You're Reading a Preview
Become a Clinical Tree membership for Full access and enjoy Unlimited articles
If you are a member. Log in here
