Key points
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Most patients with cardiac masses are asymptomatic; however, they may present with symptomatology and clinical signs suggestive of more common and rapidly debilitating syndromes such as angina, myocardial infarct, or cerebrovascular insufficiency. Therefore the presence of an intramural or intracavitary mass is usually detected on imaging undertaken to rule out other structural pathologies, such as valvular disease.
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A sequential approach to imaging that allows appropriate use of resources in a step-up fashion is usually undertaken, i.e., bedside modalities (such as transthoracic echocardiography) should be performed prior to more invasive and costly options such as transesophageal echocardiography or cardiac magnetic resonance imaging, as this may satisfactorily rule out the presence of such a mass.
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Each subsequent imaging modality provides useful information, which guides the decision on whether to excise the mass in question. Finally, biopsy or postexcision histopathological analysis may reveal the final diagnosis and tissue characterization.
Box 21.1: Introduction
Cardiac masses represent a rare and complex entity that often result from metastatic cancers or more complicated disease processes. The diagnostic process often involves multidisciplinary approaches with careful multimodal imaging consultations. Cardiac masses can be broadly categorized into tumors, thrombi, vegetations, calcific lesions, and other rare conditions. Unlike other anatomical sites in the body, cardiac masses can have significant repercussions on blood flow obstructions, formation of emboli, and can result in electrical or mechanical dysfunction as a result of interference with the underlying anatomy. Presentations of such masses need to be viewed with a full diagnostic workup which involves clinical presentation imaging, invasive and noninvasive investigations, and long-term management considerations. These masses can be further divided into subcategories including benign and malignant primary and nonneoplastic tumors, or by the anatomical site that they occupy such as intracardial or pericardial tumors which fall under the category of cardiac masses .
The process of reaching a diagnosis surrounding a space occupying lesion or mass in the heart can be done as a result of symptomology or specific incidents. The majority of tumors found in the heart tend to be benign with over a 50% being a myxoma. Primary malignant tumors are very rare accounting for less than 25% of primary cardiac tumors, and in the majority of cases these would present as sarcomas. In studies performed on autopsy results, cardiac tumors are most commonly present as metastatic malignant tumors. The prevalence of first-degree cardiac tumors is 1 in 2000 whereas autopsies and autopsy studies show a ratio of 1 in 100 for metastatic tumors. This indicates a ratio of primary to secondary cardiac tumors in the range of 20 to 1. However, there is great variation among autopsy studies with ranges of the incidence of cardiac metastases from 2.3% to 18.3% in patients with extracardiac malignant tumors .
Multimodal cardiac imaging including transthoracic echocardiography, transesophageal echocardiography, cardiac magnetic resonance, cardiac computed tomography, and fluorodeoxypositron emission tomography have a complementary and reinforcing role in the evaluation of cardiac masses. Given the diverse range of cardiac masses that can be identified both on autopsy imaging and other forms of investigation, there are currently no strict guidelines or general consensus on the diagnostic algorithm or best diagnostic approach in identifying these masses .
This chapter aims to outline a classification-based approach to identifying and diagnosing each type of cardiac mass.
Benign primary cardiac tumors
The most common type of benign cardiac tumors is myxomas which tend to present in early adulthood in the case of familial myxoma, and middle adulthood for all other types of myxoma. Myxomas are commonly located in the left atrium along the atrial septum. They are generally identified using echocardiography which shows a mildly lobar mass with heterogeneous echogenicity and are usually mobile. CT shows low attenuation with potential calcification, and CMR confirms heterogenicity. The main clinical manifestations for a myxoma include emboli, flow obstructions, and systemic symptoms .
Papillary fibroelastomas tend to present in middle or late adulthood and are commonly located on cardiac valves. Echocardiography tends to show a circular, pedunculated, nonprotruding mass which rarely interferes with valve function. CT also shows a smooth and pedunculated mass. CMR shows a highly mobile mass and could indicate the need for a TEE. Clinical manifestations include emboli; however, patients are usually asymptomatic .
Lipomas usually present during adulthood and at any site. Echocardiography shows a homogenous structure, with CT showing a smooth homogenous encapsulated structure with some fat attenuation. Clinical manifestations include arrhythmias and flow obstruction; however, most patients are usually asymptomatic .
Rhabdomyomas tend to present in infancy or early childhood on the ventricles or atrioventricular valves. Echocardiography will usually show a homogenous, slightly echogenic mass. CTs will show similar attenuation to intramural myocardium. Main clinical manifestations include flow obstruction, arrhythmias, and heart failure; however, patients are usually asymptomatic .
Fibromas tend to present in early childhood on the intraventricular septum or ventricle walls. Echocardiography shows a heterogeneous, echogenic, and noncontractible mass which can sometimes mimic hypertrophic cardiomyopathy. CT shows soft tissue attenuation with possible calcification. Patients tend to be asymptomatic; however, some may have arrhythmias .
Hemangiomas can present at any age and at any site. Echocardiography shows a highly echogenic mass which may resemble a cavity. CTs will show a heterogeneous mass with potential calcification and CMR confirms heterogenicity. Most patients are asymptomatic or experience low-grade dyspnea .
Malignant primary cardiac tumors
Angiosarcomas tend to present during early adulthood in the right atrium or pericardium. Echocardiography shows a heterogeneous highly echogenic mass. CT confirms heterogenicity and shows low attenuation with CMR also confirming heterogenicity. Main clinical manifestations include constitutional symptoms, pericardial effusion, and heart failure .
Rhabdomyosarcomas usually present in childhood and in some cases very early adulthood. They can present at multiple sites but have a tendency to present in the ventricles. Echocardiography shows normal to high echodensity. CT shows irregular shape and low attenuation with CMR showing a homogenous mass. The main clinical manifestation is heart failure .
Myxofibrosarcomas tend to present in early to middle adulthood and can present anywhere. Echocardiography shows a heterogeneous mass with normal to high echodensity. CT and CMR confirm heterogenicity, with CT also highlighting low attenuation. The main clinical manifestations include flow obstruction, pericardiac effusion, and metastases .
Lymphomas tend to present in adulthood on the right atrium and at other sites. Echocardiography can rarely differentiate size and shape. CT shows normal to low attenuation and a heterogeneous mass. The main clinical manifestations are pericardial effusion, flow obstruction, and heart failure .
Mesotheliomas tend to present in adulthood on the pericardium. Echocardiography and CMR show a heterogeneous mass and CT is able to outline the variable characteristics .
Nonneoplastic cardiac masses
Clots usually occur in adulthood in the left atrial appendage and the left ventricle. Echocardiography shows low echodensity in acute clots and high echodensity in chronic clots, with CT showing possible calcification. The main clinical manifestation is an embolus .
Vegetations are usually found in adulthood on cardiac valves. Echocardiography shows a highly mobile, protruding mass and some valvular dysfunction. CT shows low attenuation, perivalvular extension, fistulas, and abscesses. CMR shows a highly mobile mass which may lead to consideration for TEE. Main clinical manifestations include valve dysfunction, emboli, and heart failure .
Nonneoplastic calcified masses usually present in adulthood and typically in the posterior mitral annulus. Echocardiography shows high echodensity, and CT shows heterogeneous calcification. Due to signal loss CMR is not useful and thus imaging is reliant on CT. Patients are usually asymptomatic .
Pericardial cysts are usually present in adulthood on the pericardium. Echocardiography shows low echodensity with CT showing the presence of wall and fluid attenuation. The main clinical manifestation is external compression; however, most patients are asymptomatic .
Lipomatous hypertrophy usually presents in late adulthood on the atrial septum. Echocardiography shows homogenous dumbbell appearance of the atrial septum, with CT showing fat attenuation. There are rarely any clinical manifestations, but some patients may experience arrhythmias .
Box 21.2
The differential diagnosis by operative view of cardiac masses can be carried out using key investigations in a step-up approach. Essentially, upon initial presentation of a patient with manifestations possibly associated with an intracavitary or intramural mass, echocardiographic imaging may initially determine the presence or absence of said mass. Once the presence thereof is determined, subsequent imaging-based investigations are undertaken to explore further parameters concerning the mass, enabling the clinician to rule out other differentials in the process. Finally, once surgical intervention is undertaken, visual aspects of the mass and histopathological analysis then confirms the diagnosis. A detailed approach to each tumor’s surgical and clinical features may be found in 19, 20 . Fig. 21.1 depicts a flow chart outlining the differential diagnostic approach in cardiac masses.
| Diagnostic step | Details |
|---|---|
| Initial presentation | It is crucial to bear in mind that though cardiac masses—both malignant and benign in nature—are exceedingly rare entities (for a number of reasons), they represent a considerable insult to the heart and potentiate a number of debilitating and potentially lethal adverse outcomes The presence or absence of clinical manifestations associated with benign and malignant cardiac masses depends primarily on the extent to which said mass effects cardiac mechanics’ conduction or output. Such manifestations may include arrhythmias, pulmonary congestion, angina, dyspnea/orthopnea, or thromboembolic events . Unsurprisingly, when faced with such manifestations, it is crucial to first treat the acute event prior to undertaking investigations to determine the underlying cause As an example, patients with atrial myxoma (the most common benign cardiac mass) may exhibit clinical signs consistent with mitral valvular disease, such as pulmonary congestion, a systolic murmur (present in 50% of cases), loud S1 (in 32% of cases), diastolic murmur (15% of cases), or a “tumor plop”—a low-pitched, diastolic murmur heard as the tumor prolapses into the left ventricle . Additionally, depending on the thrombogenicity of the tumor, patients with atrial myxoma may also exhibit stigmata of peripheral thromboembolism depending on the vasculature affected When faced with such findings, and once acute problems have either been managed or ruled out, various imaging modalities may be undertaken to confirm the presence or absence of a mass, and subsequently to determine its location, extent, effect on surrounding tissues, and to inform preoperative decision making |
| Transthoracic echocardiography (TTE) | TTE is one of the most common modalities used in the detection and diagnosis of cardiac masses, possibly because its use is widely indicated as part of the diagnosis or follow-up of cardiovascular and thromboembolic pathologies, from atrial fibrillation to valvular disease. The fact that it can be performed bedside and is relatively inexpensive, rapid, and nonirradiating (in comparison to more specialist modalities employed downstream) makes it even more useful For example, TTE allows robust assessment for patients with suspected cardiac papillary fibroelastoma (CPF), allowing the clinician to quickly establish the lesion’s location, approximate size, attachment site, mobility, and morphology It should, however, be emphasized that TTE plays a facilitatory rather than determining role in the differential diagnosis of cardiac masses. It is insufficiently accurate to provide a definitive diagnosis or to fully inform surgical decision making: TTE is associated with suboptimal sensitivity—it fails to detect up to 38.1% of cases of CPF. However, TTE serves as a useful juncture to rule out acute cardiac masses (e.g., intracavitary thrombi that could readily embolize) or indeed to rule in certain comorbidities (in addition to a cardiac mass), such as heart failure or valvular disease, that may influence decisions around management and prognosis |
| Transesophageal echocardiography (TEE) | Following the affirmative identification of an intracardiac mass, and having ruled out the presence of an intracavitary thrombus via TTE, following up with TEE may be useful to determine with more accuracy the parameters surrounding the mass in question For intracavitary masses such as CPF or atrial myxoma, TEE with contrast may elucidate the hemodynamic effects of mass, in addition to determining with greater confidence the size, mobility, and attachment point. For example, TEE is noted to detect 15% more cases of CPF, and reportedly only misses 23.4% of cases (compared to TTE, which misses up to 38.1% of cases) TEE would also be useful in the identification of intramural masses, such as lipomatous hypertrophies of the interventricular septum (LHIS): septal hyperechogenicity on TEE would increase the likelihood of a patient’s symptoms being caused by LHIS rather than mitral valve regurgitation or congenital outflow tract obstruction. Indeed, TEE helps to confirm the location of intramural masses and properly assess the extent to which the mass obstructs cardiac inflow/outflow Notably, TEE-guided biopsy is particularly useful when faced with a lipomatous mass (seen on echocardiography as areas of hyperechogenicity). It is important to differentiate between LHIS and cardiac lipoma—the invasive (albeit benign) nature of LHIS puts patients at substantial risk of developing aberrant conduction or possibly obstructed outflow tracts |
| Specialist imaging modalities | More specialist imaging modalities may be employed following TTE and TEE, primarily with a view of determining the extent of the cardiac mass, its delineations, relationship with surrounding tissues, and tissue characterization Cardiac magnetic resonance (CMR), for instance, provides optimal delineation of the intracardiac mass and the relationship between the mass and local myocardium—informing the decision on whether the mass can or should be excised, and what the optimal surgical approach would be. It would also inform the care team whether the mass is solid, fatty, or hemorrhagic . In differentiating between cardiac lipoma and LHIS, CMR can provide useful information on the degree of mixing between adipose and muscle tissue, which would inform surgical decision making. Cardiac lipoma, for example, would show increased T1-weighted signaling on CMR and reveal the lipoma capsule and thin septations within the mass. In contrast, LHIS would similarly appear hyperintense on CMR; however, LHIS would also feature invaginations of muscular tissue and the absence of a lipomatous capsule Coronary angiography should similarly be undertaken preoperatively, for several reasons. Not only would it reveal the extent to which coronary circulation is compromised by the extent of the mass (allowing the care plan to be adjusted accordingly), but it would also reveal the route by which the mass is supplied by coronary circulation—allowing the surgical team to anticipate and prevent catastrophic hemorrhage during excision |
| Operative view and histological analysis | Intraoperative visualization and successful excision of the cardiac mass facilitate pathological examination of the tumor, and in doing so provides definitive information tumor staging and tissue characterization For example, the characteristic appearance of a CPF with a centralized core of elastic tissue surrounded by an outer layer of radiating fronds, originating from the perivalvular papillary tissue, may well confirm the diagnosis of CPF . However, further histochemical analysis may be required to rule out more malignant masses, for example liposarcoma should be ruled out in cases of suspected lipoma via gene amplification testing In malignant cases, functional metabolic imaging modalities may be undertaken as part of determining the malignancy’s staging and aggressiveness, which would aid prognostication |
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