Echocardiography is a powerful tool in the differential diagnosis of cardiac masses. Although echocardiography cannot replace pathologic examination in obtaining an exact diagnosis, characteristic features of the ultrasound images can help to differentiate these masses. Combining clinical data such as sex, age, signs of an extracardiac primary tumor, and response to therapy (anticoagulation or antibiotics) with morphologic properties, such as location, attachment site, size, mobility, texture, and number of tumors, often produces an accurate diagnosis. A correct diagnosis is crucial in therapeutic decision making, but because pathology specimens usually are obtained only during surgical resection, it is important to recognize the typical indirect and direct echocardiographic features of the various tumors. Echocardiography is the technique of choice; further, because of its close proximity to the heart, transesophageal echocardiography (TEE) in general is superior to transthoracic echocardiography (TTE).

Some normal structures may mimic cardiac masses: the eustachian (inferior caval vein) valve, the thebesian (coronary sinus) valve, a Chiari network, crista terminalis, pectinate muscles, atrial chords, a moderator band, trabeculations, ventricular noncompaction, the apical form of hypertrophic cardiomyopathy, and the ridge between the left upper pulmonary vein and left atrial appendage may all be misinterpreted as cardiac masses (see Chapter 3).1 With the development of three-dimensional real-time TEE, multislice imaging of cardiac masses is possible, allowing for better visualization of tumor morphology and location, which in turn may help to improve decision making during surgical resection.2 Real-time three-dimensional TEE may become the technique of choice for noninvasive evaluation of tumor size.3

Cardiac tumors may be primary or secondary and malignant or benign. Of all primary cardiac tumors 75% are benign and 25% are malignant. Of the benign tumors in McAllister and Fenoglio’s observations of 533 primary tumors,4 24.4% were myxomas, 8.4% were lipomas, 7.9% were papillary fibroelastomas, and 6.8% were rhabdomyomas. Fibromas, hemangiomas, teratomas, atrioventricular nodal mesotheliomas, granular cell tumors, pericardial cysts, and bronchogenic cysts accounted for fewer than 5% each. In the malignant group, angiosarcoma (7.3%) and rhabdomyosarcoma (4.9%) were the most frequent, whereas mesothelioma, fibrosarcoma, malignant lymphoma, extraskeletal osteosarcoma, neurogenic sarcoma, malignant teratoma, thymoma, leiomyosarcoma, liposarcoma, and synovial sarcoma were rare conditions. Secondary tumors are more frequently carcinomas than sarcomas, but all types of tumors may be found.

Myxoma is the most frequent of the benign cardiac tumors, accounting for 30% to 50% and presenting with a female preponderance (Figure 19–1).5 They occur most often in the third through sixth decades, and more than 90% are sporadic. Left atrial localization is most frequent (75%),4,6,7 although 18% are found in the right atrium, 4% in the right ventricle, and another 4% in the left ventricle. Myxomas can present as multiple lesions in the left atrium and may be bilateral, whereas a ventricular location occurs more frequently in children. Myxomas typically are pedunculated, polypoid, friable tumors, sometimes possessing a smooth and rounded surface (Figure 19–2). They are commonly lobulated but can have a villous surface and typically are attached by a narrow stalk to the endocardial surface on the limbus of the left atrial side of the fossa ovalis. However, any other site of attachment is possible.4 Myxomas contain a mucopolysaccharide myxoid matrix and have a nonhomogeneous appearance on TEE because of the presence of channels, cystic areas, hemorrhage, or calcifications (Figure 19–3). A familial form of myxoma has been described with an autosomal dominant transmission.4 It occurs at a younger age, is seen more frequently in atypical locations, and is characterized by a higher recurrence rate after surgical resection.8,9 In contrast, the familial form has a male preponderance and is more frequently bilateral. Routine screening of first-degree relatives of patients with myxoma is therefore indicated, especially in young patients or if multiple tumors are found. Patients with a familial history of myxoma also should be screened carefully for multiple or atypically located myxomas, and repeated postoperative echocardiographic examinations are necessary to detect recurrence.10 This familial variety may be part of a syndrome (Carney’s complex, NAME syndrome, or LAMB syndrome).11

A typical triad of symptoms includes embolization, obstruction, and constitutional symptoms such as dyspnea, position-related palpitations, syncope, congestive heart failure, and even sudden death. Emboli may cause neurologic deficit or coronary events, but any systemic vessel may be involved. Obstructive symptoms, detected as turbulence on color-flow Doppler, can present with any intracavitary tumor and may involve the mitral or tricuspid valve (atrial myxomas), pulmonic or aortic valve (ventricular myxoma), or venous inflow to the atria.12,13 If the mitral or tricuspid valve is obstructed, a typical tumor “plop” can be heard after the second heart sound on auscultation.

Except for detecting ventricular locations, TEE is superior to TTE. It allows for detailed description of tumor morphology and attachment, and for detection of multiple tumors. A bilateral dumbbell-shape myxoma may pass through the foramen ovale and may be fixed to the margin of this foramen.14 Right atrial myxomas tend to be more solid, have wider attachments, and may be fixed to the inferior rim of the fossa ovalis, the tricuspid valve, or the eustachian valve. Obstruction of the tricuspid valve or caval veins is possible.15,16 Left ventricular myxomas are rare, occur at younger age, and are three times more frequent in women than in men. In these cases, cerebral embolism is frequent and subaortic or aortic obstruction is possible. Right ventricular myxomas also are infrequent and may cause pulmonary embolism and outflow obstruction.

Rhabdomyoma is the most frequent cardiac tumor in infants and children and is associated with tuberous sclerosis.17,18 Of these, three-fourths occur before the age of 1 year. It is usually multiple and frequently involves the right ventricular myocardium. Occasionally, it may project into the ventricular cavity and even move freely as a pedunculated tumor.19 It can cause obstruction of the right ventricular outflow tract, and diagnosis by fetal echocardiography before birth is possible. Rhabdomyomas may regress spontaneously after birth.

Fibromas are ventricular intramural tumors that are frequently calcified. They occur more frequently in infants and children.20

Papillary fibroelastomas are small (usually <1 cm), homogeneous, mobile tumors, often with a stalk, originating from the cardiac valves or, less frequently, from the ventricular endocardium. Papillary fibroelastomas originate from the atrial side of the atrioventricular valves or from either side of the semilunar valves and frequently are a coincidental finding. The most common locations are on the aortic valve cusps (44.5%) and mitral valve leaflets (36.4%). Attachment to the ventricular septum or close to the left ventricular outflow tract or to the subvalvular mitral apparatus has been described (Figure 19–4). They can cause angina and infarction by coronary ostial occlusion or embolism,21,22 but systemic embolism is also possible so surgical resection is advocated. They occur most commonly in patients older than 50 years but rarely occur on the right side of the heart.17,23,24 Multiple fibroelastomas occur in 6.8% to 7.5% of cases.25 Fibroelastomas have a short pedicle with multiple papillary fronds, and have to be differentiated from Lambl excrescences, which are degenerative in origin and arise from the ventricular side of the semilunar valves along the coaptation line (Figure 19–5).17 The exact histogenesis of papillary fibroelastoma is uncertain, and although most investigators classify it as a neoplasm, it may represent exuberant organization of thrombi, similar to Lambl excrescences.25 Colocalization of Lambl excrescences and fibroelastomas suggest a common origin. A virus-induced tumor hypothesis also has been proposed. Differential diagnosis from endocarditis and vegetations may be difficult and depends on the clinical presentation of the patient. However, in contrast to endocarditis, valvular dysfunction (insufficiency) is uncommon.

Lipomas affect the entire heart and pericardium and can be massive.26 They may produce a pericardial effusion. Intramyocardial lipomas are well encapsulated and small.17 Occasionally, a lipoma may arise from the mitral or tricuspid valve, and differential diagnosis with a myxoma becomes necessary.27

Lipomatous hypertrophy of the interatrial septum is a form of hyperplasia of adipose tissue (Figure 19–6). It presents as atrial septal thickening with a bilobed or “dumbbell” appearance due to sparing of the fossa ovalis.

Most malignant primary cardiac tumors are sarcomas, most frequently angiosarcomas originating in the right atrium or pericardium.28,29 They demonstrate a male preponderance. Angiosarcomas often (25%) grow partially intracavitary and may cause caval or valvular obstruction.30 Cardiac rupture,6 right heart failure, and pericardial tamponade have been described.